Chapter 14 Sleep, Dreaming & Circadian Rhythms

What are all the other stages of sleep called (except emergent stage 1)?

NREM sleep - The nature of NREM sleep changes over the course of the night. Starting with deeper waves getting progressively shallower

What happens when researchers adjust zeitgebers such as light/dark in lab experiments?

subjects circadian cycles will adjust accordingly (lengthen or shorten)

What is melatonin?

A hormone synthesized from the neurotransmitter serotonin in the pineal gland. - Exogenous melatonin works to re-correct circadian clock in some individuals. good for insomniacs who have melatonin deficiency.

What is chronobiotic?

A substance that adjusts the timing of internal biological rhythms

How is REM sleep controlled in the caudal reticular formation?

A variety of nuclei scattered throughout the caudal reticular formation - one site controls reduction of core-muscle toe, another EEG desynchronization another for rapid eye movement etc.

What does the anterior hypothalamus promote?

sleep

What are hypnotic & antihypnotic drugs?

Drugs that increase sleep and drugs that reduce sleep

What research findings support the alternative explanation on the effects of long-term sleep reduction?

(Although few studies of long-term sleep patterns have been conducted, and some conducted are not sufficiently thorough, a clear pattern has emerged) Comparing large sample of short sleepers (6 hrs or less) & long sleepers (8+ hrs) on 48 diff. measures, screened out volunteers who were ill or under stress / pressure - and added a control group who slept amt that they felt was right for them. Results: there were no differences between the 2 groups on any of the other measures, no indication that short sleepers were suffering. Negative characteristics reported in other studies likely reflected stress experienced by some, when not controlled for.

What were the researchers testing by spraying water on sleeping participants? And what were the results.

(Kleitman) Tested to see if external stimuli can be incorporated into dreams, and yes subjects had dreams about water dripping on them and others. 1) However when tested with other stimuli the effect was not as robust. Water seems to be one of the best stimuli to incorporate into dreams 2) One other effective stimuli was pressure on limbs 3) Personally relevant (meaningful) words also can become incorporated into dreams

What are sleep spindles?

1 to 2 second burst of high frequency waves of 12-14 Hz waves

Describe the 2 studies on healthy volunteers that reduced their nightly sleep for several weeks or longer

1. 16 volunteers slept for 5.5. hours / night - 60 days => only detectable deficit was a slight deficit on test of auditory vigilance 2. 8 volunteers reduced their nightly sleep by 30 mins every 2 weeks until they reached 6.5 hours per night, then reduced sleep by 30 mins every 3 weeks until they reached 5 hours, then by 30 mins every 4 weeks thereafter. After a participant indicated lack of desire to reduce sleep further, he/she spent 1 month sleeping the shortest duration of nightly sleep that had been achieved, then 2 month sleeping the shortest duration + 30 minutes. Finally each participant slept however long was preferred each night for 1 year. The minimum duration of nightly sleep achieved during this experiment was 5.5 hours for 2 participants 5 hours for 4 participants 4.5 hours for 2 participants Reduction in sleep time was associated w/ an increase in sleep efficiency, decrease in amt. of time it took to fall asleep after going to bed, decreases in no. of nighttime awakenings and an increase in % of stage 4 sleep. After participants had reduced their sleep to 6 hours per night - they experienced daytime sleepiness. Became a bigger problem as sleep time was increased. But no deficits in mood, medical or performance tests administered throughout the experiment. Unexpected followup the following year, found all participants sleeping less than they had previously, between 7 and 18 hours less per week with no excessive sleepiness.

Discuss adaptation theories of sleep

1. Adaptation theories focus more on when we sleep than on the function of sleep. 2. Sleep is not a reaction to the disruptive effects of being awake, but the result of an internal 24-hour clock (circadian rhythm). 2. We have evolved to sleep at night because sleep protects us from accidents and predation during the night (before advent of artificial lighting) 4. Some theories propose that sleep plays no role in efficient physiological functioning of the body - sleep evolved to conserve energy resources and to make us less susceptible to mishap (predation) in the dark. 5. These theories suggest that sleep is like sex in that we are highly motivated to engage in it but we don't need it to stay healthy In circadian theories, sleep is the result of an internal timing mechanism - we are programmed to sleep at night (regardless of what happens during the day) we evolved to sleep at night because it protects us - keeps us out of trouble and conserves energy

What are the 5 major pieces of evidence that slow-wave sleep serves the main restorative function?

1. After people have been sleep deprived, they regain most of their lost stage 4 sleep, but only a small proportion of their total lost sleep. 2. After people have been sleep deprived, the slow-wave sleep EEG is characterized by an even higher proportion than usual of slow waves thus people who sleep only 6 hrs per night normally get as much slow-wave sleep as people who sleep 8 hours 3. If people take a nap in the morning after a full nights sleep their nap time EEG shows few slow waves and nap does not reduce duration of the following night's sleep 4. People who gradually reduce their usual sleep time get less stage 1 & 2 sleep, but their slow-wave sleep remains the same. 5. Repeatedly waking individuals during REM sleep produces little increase in sleepiness the next day - whereas repeatedly waking an individual during slow-wave sleep has major effects

Which 4 areas of the brain are involved in sleep?

1. Anterior hypothalamus (promotes sleep) 2. Posterior hypothalamus (promotes wakefulness) 3. reticular formation (reticular activating system) 4. caudal reticular formation

Describe the 3 lines of experiments that point to the existence of other circadian timing mechanisms beside the SCN

1. Bilateral SCN lesions have been shown to leave some circadian rhythms unaffected while abolishing others (in certain circumstances) 2. Bilateral SCN lesions do not eliminate the ability of all environmental stimuli to entrain circadian rhythms (SCN lesions can block entrainment by light but not by food or water availability) 3. Cells from other parts of the body display free-running circadian cycles of activity when maintained in tissue culture

What are the 4 pieces of evidence that the reticular formation is involved in sleep?

1. Cats with midcollicular transection (cerveau isolé) displayed continuous slow-wave sleep EEG patterns 2. Lesions at midcollicular level that damaged core of reticular formation but left sensory fibres intact produced a cortical EEG indicative of continuous slow-wave sleep. 3. Electrical stimulation of pontine reticular formation desynchronized cortical EEG and awakened sleeping cats 4. Cats with a transection of caudal brain stem (encéphale isolé preparation) displayed a normal sleep-wake cycle of cortical EEG

what were the other 4 results in the testing of common beliefs about dreaming?

1. Dreams last in real time 2. People who claim they do not dream report dreaming when they are awakened during REM episodes, although not as often as normal dreamers. 3. Penile erections do not differ between dreams with and without frank sexual content & babies have REM-related penile erections 4. Sleeptalking (somniloquy) cand sleepwalking (somnambulism) do not occur only during dreaming. a) Sleeptalking can occur during all sleep stages, but is ost common at times when perosn is actually briefly awake, but unaware of it. (ie. during transition to wakefulness) b) Sleepwalking is most common in SWS (stage 3/4) not REM sleep (REM -> sleep paralysis)

What are the 3 findings in comparative analysis regarding the importance of sleep?

1. Evidence that animals who are at increased risk of predation when they sleep still do so and Many have evolved complex mechanisms that enable them to sleep. e.g. Dolphins sleep w/ only half of their brain at a time (so other half can control resurfacing for air) 2. The fact that most mammals and birds sleep suggests that the primary function of sleep is not some special higher-order human function (it's not for reprogramming our complex brain, or for cathartic release or maintaining mental health) 3. Large between-species differences in sleep time suggests that although sleep may be essential for survival it is not necessarily needed in large quantities - Horses/deer get by on 2-3 hours per day - Sleep patterns of mammals and birds in their natural environments vary substantially from their sleep patterns in captivity (in the wild when food is short or during periods of migration some mammals sleep little compared to when they are in captivity. 4. There is no strong relationship between a species' sleep time and its level of activity, body size or body temperature. (such as predicted by recuperation theories) E.g. Giant sloths sleeping 20 hrs per day - is a strong argument against the theory that sleep is a necessary to recoup energy expenditure. - There are a large between-species differences in sleep time, suggesting sleep may be essential, but perhaps not in large quantities. However, Adaptation theories correctly predict that daily sleep time is related to how vulnerable animal is while asleep and how much time it must spend to feed and take care of other survival requirements. E.g. Zebras must graze almost continuously to get enough to eat and are very vulnerable to predatory attack when they sleep - they sleep only 2 hours per day. But African lions often sleep almost continuously for 2-3 days after they have gorged themselves on a kill (herbivores sleep less than omnivores, omnivores sleep less than carnivores - thus adaptive theory makes more sense)

How can dreaming and REM sleep be dissociated? explain the findings

1. Forebrain lesions can abolish dreaming but spare REM sleep. - 70% of prefrontal lobotomy patients report cessation of dreaming - If you lesion the temporal-parieto-occipital junction 100% of individuals report no dreams & are impaired in visual imagery when awake. - When different brain regions in the visual system are lesioned, resulting effects (prosopagnosia, colouragnosia etc) will also be experienced in their dreams. - the only type of visual system lesion that does not effect dreaming is primary visual cortex lesions (does not effect reports of dreams) Thus dreaming must be very top down. 2. Brainstem lesions can eliminate REM sleep, but don't abolish dreams. - Certain drugs abolish REM sleep but will not abolish dreaming. - Antidepressant drugs (SSRis and tricyclics suppress REM sleep. Thus REM sleep is not necessarily as critical as people think (there is a large % of population who don't get REM sleep and don't have any negative cognitive effects). There is no learning and memory impairment in people taking SSRIs (therefore is REM sleep really necessary for LT memory?)

What 2 behavioural approaches help to reduce effects of jet-lag?

1. Gradually shift sleep-wake cycle in days prior to flight 2. Administering treatments after the flight that promote required shift in circadian rhythm (e.g. exposure to intense light early in morning following east-bound flight, accelerates adaptation to phase-advance) or a good workout early in the morning of the 1st day after an east-bound flight might accelerate adaption to phase advance.

List the 4 REM-related mysteries taught in class

1. How do organisms benefit from this high-energy consuming process? - there is no obvious reason why we go thru such a high energy consuming process when it's not even necessary (REM sleep deprivation has no affect on cognitive function) 2. How do organisms benefit from this risky process? - It's risky because a) there is a sharp change in heart rate - cardiac emergencies most often occur during sleep. b) Homeothermy: body temp regulation is suspended during sleep. Dangerous for the brain because the brain needs a tight monitoring for proper functioning 3. Why do babies display so much REM-like sleep? - They spend a lot of time sleeping

Moderate amounts of sleep deprivation (reducing sleep by 3 to 4 hrs per night) has 3 consistent effects, what are they?

1. Increased sleepiness (feel sleepy & fall asleep more quickly) 2. Increased negative affect (disturbance on written tests of mood) 3. Perform poorly on vigilance tests (radar screed, driving etc.)

Describe the 2 sorts of long-term sleep reduction studies

1. Monophasic - Studies in which subjects sleep nightly - gradual reduction in sleep - Military study (Friedman)" Reduced sleep over weeks by 1/2 hour until person couldn't' take any more reductions, then add 30 mins back on , then ask them to maintain that same amt of sleep. (achieved 4.5 - 5.5 hours per night) minimum seems to be in 5 hour range - Subjects experienced increased sleepiness in day, when sleep went below 6 hrs / night, but showed no notable changes in mood, physical health, or performance on tasks of vigilance or memory - After 1 year all subjects had reduced sleep by 1 - 2.5 hr w/ no excessive sleepiness - Subjective responses were often not in line w/ objective measures or w/ performance at work /school. - Other studies have reported similar results, except one study reported a decline in cognitive task performance when sleep was reduced below 5 hrs 2. Polyphasic - Studies in which subjects only nap. - Regimented napping (see DaVinci sleep schedules) - Only succeeds if you can run your life at your own schedule - Evidence that polyphasic sleep was the norm until recently - Most mammals & human infants sleep more than once per day - Most adults display once per day, but display polyphasic cycles of sleepiness (late in morning, late in afternoon) Both reduce sleep significnatly

Why is the REM = Dreaming an oversimplification?

1. NREM dreams exist (if you ask the right questions) - stage 1: 89-90% of wake-ups had shorter dreams more hypnagogic - stage 2-3: 50-70% of wake-ups - earlier in night: more thought-like, less vivid, less visual, less conceptual - later in night: longer, hallucinatory, indistinguishable from REM dreams As night progresses dreams become more narrative-like

What are 3 lines of evidence that suggested to early researchers that narcolepsy resulted from an abnormality in mechanisms that trigger REM sleep?

1. Narcoleptics often go directly into REM sleep when falling asleep 2. Hypnagogic hallucinations 3. Sleep paralysis

What are the 2 types of sleep apnea disorders?

1. Obstructive sleep apnea - results from obstruction of the respiratory passages by muscle spasms or atonia (lack of muscle tone) Often occurs in people who are vigorous snorers 2. Central sleep apnea - results from failure of the central nervous system to stimulate respiration.

What are some of the other REM-sleep-related disorders discovered?

1. Patients who have little or no REM sleep. - disorder is rare - presumably involves damage to REM-sleep controllers in caudal reticular formation. Patient did not appear to be adversely affected - completed law school, and started law practice. 2. REM sleep without core muscle atonia - thus are not prevented from acting out dreams. REM sleep without atonia is presumably caused by damage to nucleus magnocellularis or to an interruption of its output

What are 2 other forms of insomnia from specific medical causes?

1. Periodic limb movement disorder: characterized by periodic involuntary movements of limbs (usually twitches of legs during sleep). Patients are usually unaware of the nature of their problem, but complain of poor sleep and daytime sleepiness. 2. Restless legs syndrome: complain of hard to describe tension or uneasiness in legs that keeps them from falling asleep. Both disorders are chronic once established. More research is needed, but some dopamine agonists can be effective

What are the 2 theories that propose why we sleep?

1. Recuperation theories 2. Adaptation/circadian theories of sleep

What are 2 orexin related research results?

1. Reduced levels of orexin in cerebrospinal fluid have been found in living narcoleptics & in the brains of dead ones. 2. The number of orexin-releasing neurons has been found to be reduced in the brains of narcoleptics

What are 2 other symptoms of Narcolepsy?

1. Sleep paralysis: Inability to move just as one is falling asleep or waking up 2. Hypnagogic hallucinations: Dreamlike experiences during wakefulness Many healthy people occasionally experience one or other or both.

The identification of circadian genes have led to what 3 important discoveries?

1. The same or similar circadian genes have been found in many species of different evolutionary ages (bacteria, flies, fish , frogs, mice and humans) indicating that circadian genes evolved early in evolutionary history and have been conserved in many descendant species 2. The key fundamental molecular mechanism of circadian rhythms seems to be gene expression - transcription of proteins by the circadian genes displays a circadian cycle. 3. Provided a more direct method of exploring the circadian timing capacities of other parts of body. Molecular timing mechanisms similar to SCN exist in most other cells of the body. Although most cells contain these timing mechanisms, these cellular clocks are normaly entrained by neural and hormonal signals from the SCN

There are 2 general theories around the function of REM sleep, what are they? What is the problem with both of these?

1. Those that say REM sleep is important to one's mental health 2. Those that say REM sleep is necessary for processing memories Both these theories have problems explaining that tricyclic antidepressants (SSRIs) which reduce REM sleep to virtually nothing, have no ill effects on health and no observable effects on cognitive functioning There is no conclusive evidence for function of REM sleep in humans yet.

List 5 complications associated with chronic use of benzodiazepines as hypnotic agents

1. Tolerance - often short and rapid; patient must take larger doses to maintain drugs efficacy and often become addicted (e.g. Ativan) 2. Cessation after chronic use causes insomnia 3. Benzos distort normal pattern of sleep: increase duration of stage 2 sleep and decrease duration of stage 4 and REM sleep 4. Benzos lead to next-day drowsiness - increase car accidents 5. Chronic use substantially reduces life expectancy

What does the caudal reticular formation involved in?

Controls REM sleep.

What happens if human subjects are REM-sleep deprived?

2 consistent effects: 1. Participants display a REM rebound - have more than the usual amount of REM sleep for the 1st 2 or 3 nights 2. With each successive night of deprivation, there is a greater tendency for participants to initiate REM sequences - thus as REM-sleep deprivation proceeds, participants have to woken up more frequently. eg. 17x 1st night, 67x 7th night

How long does it take for performance deficits observed after extended periods of sleep deprivation to disappear?

4 hours of sleep eliminated performance deficits produced by 64 hours of sleep deprivation

What have efforts to demonstrate the hypnotic effects of serotonergic drugs focused on and why?

5-hydroxytryptophan (5-HTP) The precursor of serotonin 5-HTP can pass thru the blood-brain barrier but serotonin can't

How long does each cycle between stage 1 and 4 tend to take? How do the stages normally cycle?

90 minutes Once you reach stage 4, you stay there for some time, then cycle back thru stages: 4 -> 3 -> 2 ->1. The rest of the night repeats cycling through the stages, although w/ more stage 3 & 4 earlier in night, and more emergent stage 1(and less 3 & 4) as the night progresses. - fact that SWS sleep tends to happen earlier has led to some researchers concluding that this is evidence for their adaptive imporatance - Epoch system is going out of favour w/ new digital records that now exist = anti-sleep stage researchers.

What do all recuperation theories of sleep imply?

All imply that sleepiness is triggered by a deviation from the homeostasis (internal physiological stability) caused by wakefulness and sleep is terminated by a return to homeostasis The physiological disruption tends to differ in diff. theories. e.g. function of sleep is to restore energy levels

Describe and name the pre-sleep brain electrical activity

Alpha waves: bursts of 8-12 Hz EEG waves

Why did the practice of diagnosing neurotic pseudoinsominacs stop?

Because insomnia was not necessarily a problem of too little sleep, it is often a problem of too little undisturbed sleep.

Why did research turn to serotononergic drugs as potential effective hypnotics?

Because the raphé nuclei which are serotonergic have been shown to play a role in sleep.

Why do many people think they have a sleep disorder when they don't?

Because they are pressured by expectations, friends, doctors and their own to sleep 8+ hours per day. They spend more time in bed than they should & have difficulty getting to sleep. Anxiety associated with inability to sleep makes it even more difficult. Can be helped by counselling that convinces them to go to bed only when they are very sleepy. Others have more serious problems

What is Recuperation Theory? What are its 3 predictions about sleep deprivation?

Being awake disrupts the body's homeostasis: sleep acts to restore it. Sleep fixes the damage/dysregulation that accumulates when you're awake 1. long periods of wakefulness will produce physiological and behavioural disturbances 2. These disturbances will grow steadily worse as sleep deprivation continues 3. After a period of sleep deprivation ends, much of the missed sleep will be regained

What are the most commonly prescribed hypnotic medications?

Benzodiazepines (e.g. Valium & Librium) Increase drowsiness, decrease time it takes to fall asleep, reduce no. of night awakenings, increases total sleep time - GABAa agonists -> alleviate anxiety and addictive

What are microsleeps?

Brief periods of sleep typically about 2-3 secs long during which eyelids droop and subjects become less responsive to external stimuli - although person remains sitting or standing Disrupts performance on vigilance tests as do those sleep-deprived subjects who are not experiencing microsleeps

Who was Tony Wright, what did he do?

Broke Randy Gardner's record of consecutive wakefulness. 266 hours total. Weren't man ill effects other than fatigue and cognitive effects

Where is orexin synthesized in the brain?

By neurons in the region of the posterior hypothalamus - linked to the promotion of wakefulness Although they project diffusely throughout the brain, they show many connections with neurons of the reticular formation - the other wakefulness-promoting area of the brain Currently studying orexin circuits in normal sleep-wake cycles

What are free-running circadian sleep-wake cycles?

Circadian rhythms in a constant environment and their duration is called the free running period. In a lab devoid of zeitgebers (no temporal cues), humans and other animals maintain all circadian rhythms in this constant environment. Typically slightly longer than 24 hours, more like 25 hours under constant moderate illumination Which means our internal biological clock runs slow in constant environments Free running sleep-wake cycles of one subject = 25.3 hour intervals of sleep Melotonin (chronobiotic) concentrates change drastically w/ light conditions

What are the 3 classes of antihypnotic drugs?

Cocaine-derived stimulants Amphetamine-derived stimulants Tricyclic & SSRI antidepressants

What is executive function?

Cognitive abilities that appear to depend on the prefrontal cortex (e.g. innovative thinking, lateral thinking insightful thinking and assimilating new info to update plans & strategies)

What is the alternative interpretation of the effects of long-term sleep reduction?

Consistent with the acknowledged plasticity of the adult human brain, brain needs a small amount of sleep each day, but will sleep much more under ideal conditions because of sleep's high positive incentive value. The brain then slowly adapts to the amount of sleep it is getting, even thought this may be far more than it needs, and is disturbed by any sudden reduction in sleep.

What does the free-running sleep-wake cycles evidence support?

Despite variations in the physical and mental activity, the regularity of free-running sleep-wake cycles supports the dominance of circadian factors over recuperative factors in the regulation of sleep.

What happened when Bremer transected caudal brain stems (encéphale isolé)?

Disconnected brain from rest of nervous system. Did not disrupt normal cycle of sleep EEG and wakefulness EEG of cats.

What happened when Bremer severed cats' brain stems between their inferior colliculi and superior colliculi (cerveau isolé)?

Disconnected forebrains from ascending sensory input. Put cats into almost contiuous slow-wave sleep

Lesions to the suprachiasmatic nuclei result in what?

Disrupt the various circadian cycles including sleep-wake cycles but don't greatly affect amount of time mammals spend sleeping, they abolish the circadian periodicity of sleep

What is first-night phenomenon?

Disturbance of sleep observed during 1st night in sleep lab

If optic tracts are cut after the optic chiasm (between optic chiasm and lateral geniculate nucleus), what happens to the ability of the light-dark cycle to entrain circadian rhythms?

Does not affect the ability of light-dark cycles to entrain circadian rhythms

What is hypnagosia?

Dreamlike transitional state between wakefulness & sleep. Alpha waves, sometimes accompanied by hallucinations, dreams of falling, body twitches (that throw you awake) - Found that what you do during the day effects imagery during hypnagosia (e.g. tetris effect, dreaming of game - even in temporal lobe amnesics who can't remember playing it.)

What is Hobson's activation-synthesis theory?

During REM sleep many brain-stem circuits become active and bombard the cerebral cortex w/ neural signals. Thus info supplied to the cortex during REM sleep is largely random and the resulting dream is the cortex's effort to make sense of these random signals. - Brain stem cells mainly in reticular formation become active and send signals to cortex. Random signals are based on their connectivity Result in dream that cortex is just trying to figure out - Like trying to make sense of an inkblot - there is no point to dreaming at all Later theory thought that it was a spillover from brains work during the day. - Under wakeful conditions neural signals are produced by stimuli from outside world - same circuits are working at night.

What are the 3 standard psychophysiological bases for defining stages of sleep?

EEG electroencephalogram - brain electrical activity - on skull EOG electrooculogram - eye movement - above/below & beside eye EMG electromyogram - neck muscles - chin or neck - must take all three measures concurrently in order to define sleep stages

How is sleep scored and categorized (ie. studied?)

EEG records blocked off into periods of time (researchers decide what a reasonable chunk of time is), then they count instances of various events within the EEG. - Like wave forms, sleep spindles, K complexes etc.) Until 2007- researchers were using different epochs, but now there is a standard used of 30 secs.

If optic nerves are cut before the optic chiasm (between retina and optic chiasm), what happens to the ability of the light-dark cycle to entrain circadian rhythms?

Eliminates the ability of light-dark cycle to entrain circadian rhythms As w/ Blind people w/ retinal damage - suprachiasmatic nucleus not getting light / dark information

What effects result from a pinealectomy ?

Elimination of melatonin production appear to have little effect. Pineal gland plays a role in the development of mammalian sexual maturity but its functions after puberty are not obvious

Describe the correlational studies that challenged the belief that sleeping 8 hours or more per night is ideal for promoting optimal heath and longevity

Epidemiological Data Studies started w/ a sample of healthy volunteers and followed their health for several years. Both studies results are uniform Japan: 104,010 volunteers - 10 yrs - fewest deaths occurred among people sleeping between 5 - 7 hrs per night - far fewer than among those sleeping 8 hours per night. - These studies provide strong evidence that sleeping less than 8 hours is not a risk to life that it is often made out to be - showed optimal hours of sleep to between 5 and 7 hours - but correlational

How does the sleep of mammals, birds & humans differ from amphibians, reptiles, fish and insects?

Evidence of sleep in reptiles is less clear. Some display periods of inactivity and unresponsiveness, but the relationship of these periods to mammalian sleep has not been established

What is the function of the pineal gland in reptiles, amphibians, and fish?

Has inherent timing properties and regulates circadian rhythms and seasonal changes in reproductive behaviour thru its release of melatonin. Function in humans and other mammals is less apparent.

What is the circadian sleep-wake cycles

Humans take advantage of daylight to take care of biological needs and sleep much of the night Nocturnal animals (rats) sleep for much of the day and stay awake at night. Our bodies adjust in a variety of ways to meet the demands of the light and dark environment

Sleep disorders fall into what 2 complementary categories?

Hypersomnia & Insomnia

How does shift work differ from jet lag?

In shift work, the zeitgebers stay the same but workers are forced to adjust their natural sleep-wake cycles to meet demands of changing work schedules.

What are the results of sleep deprivation on physical performance?

Inconsistent - which goes against the belief that a good night's sleep is essential for optimal motor performance. (only a few measures are affected, even after lengthy deprivation periods)

What is the difference between the Initial stage 1 and the Emergent stage 1?

Initial stage 1 EEG has no accompanied EOG or EMG changes, but the Emergent stage 1 EEG has both REMs and loss of tone in core muscles (atonia, sleep paralysis).

What are some of the animal research results of 5-HTP?

Injections of 5-HTP can reverse insomnia produced in both cats and rats by the serotonin antagonist PCPA - but they don't appear to be of therapeutic benefit in human insomnia.

What are circadian rhythms?

Internal biological clocks - Cycles of approximately 24 hours

Suprachiasmatic Nuclei

Internal timing mechanism in the medial hypothalamus

How did Hobson change his activation synthesis model after his stroke?

Later Hobson had a stroke in brain stem nuclei and became disillusioned with his theory. He lost the ability to sleep & dream for 3 weeks, hallucinated vividly while awake. Thought there was something more going on. Saw it as a virtual training ground (e.g. when infant is in sensitive state, practices without ext. stimuli when sleeping. In adults important for decision making, scenarios, stimulation of possible scenarios) = Virtual Trainer

What was the Leonardo da Vinci legend and what did study did it stimulate? (DaVinci Sleeping Schedule - Polyphasic sleep)

Legend has it that he napped 15 mins every 4 hours thereby limiting his sleep to 1.5 hours per day. Has been replicated in several experiments (Claudio Stampi) 1. Participants required a long time (several weeks) to adapt to polyphasic sleep schedules. - Critical to do the transition period slowly (like a drug, you need to go sleep it slowly, not go cold turkey ) 2. Once adapted, participants were content and displayed no deficits on performance tests 3. Leonardo's 4-hour schedule works well in unstructured working situations (e.g. around the world solo sailboat races) - subjects often vary the duration of the cycle without feeling negative consequences 4. Most people display a strong preference for a particular sleep durations (e.g. 25 mins) and refrain from sleeping too little (leaving them unrefreshed) or too much (leaving them groggy = sleep inertia) 5. When individuals first adopt a polyphasic sleep cycle, most of their sleep in slow-wave sleep, but eventually they return to a mix of REM and slow-wave sleep (1 nap might be REM sleep and the next SWS)

Where is the pineal gland?

Located on the midline of the brain just ventral to the rear portion of the corpus callosum

What did Moruzzi and Magoun propose about the reticular formation as a result of these 4 pieces of evidence?

Low levels of activity in reticular formation propose sleep and high levels of activity produce wakefulness. Often called the reticular activating system (although maintaining wakefulness is only one function of the many nuclei that it comprises).

Describe the brain electrical activity for alert wakefulness

Low-voltage, high -frequency waves

Describe stage Initial 1 sleep

Low-voltage, high frequency signal similar to but slower than alert wakefulness (Theta waves)

What are manifest dreams & latent dreams?

Manifest dreams: disguised versions of our real dreams (latent dreams) - translated into an endurable form. Thus the key to understanding clients psychological problems was to expose the meaning of their latent dreams thru interpretation of their manifest dreams

Describe the circadian cycle of body temperature

Many animals display a circadian cycle of body temperature related to their circadian sleep-wake cycle. They tend to sleep during their falling phase of body temp cycle and awaken during rising phase

What is the photopigment in these special photoreceptors?

Melanopsin

Is melatonin a soporific or a timing adjuster of mammalian circadian cycles?

Melatonin should be considered a chronobiotic - thus adjusts timing of internal biological rhythms rather than as a soporific

Explain the theory that dreams are the organization of unconsciously reactivated memories

Memories are activated as a result of activity in the brain and that activity is strung together to create a narrative (ie. making use of random activity as a means of exploration) This is cross between the first 2 theories (activation synthesis and training ground)

What is Narcolepsy, and what are it's 2 prominent symptoms?

Most widely studied disorder of hypersomnia. 1. Severe daytime sleepiness, and inappropriate sleep attacks (10-15 mins) e.g. while talking, eating, scuba diving, making love 2. Cataplexy: Recurrent losses of muscle tone during wakefulness, often triggered by emotional experiences. In mild form, it may simply force patient to sit down for a few seconds. In extreme form, patient drops to the ground as if shot, and remains there for a minute or 2 - fully conscious

Are cones & rods necessary for entrainment of photoreceptors by light?

No

Do the above list of physiological changes due to sleep deprivation have any consequences for health or performance?

No

Are free-running circadian cycles learned?

No, even rats born and raised in constant environments display regular free-running sleep-wake cycles that are slightly longer than 24 hrs.

Does the decline in immune function due to sleep deprivation make subjects more susceptible to infection?

No, immune system is complicated and decline in one aspect is often compensated for by other changes. Cold viruses exposed to 153 volunteers. Those reporting sleeping less than 8 hours per night were not more or less likely to become infected but were more likely to develop cold symptoms

What EEG signature can be seen in stage 3 sleep?

Occasional delta waves: largest and slowest EEG waves with a frequency of 1-2 Hz

Why are free-running circadian sleep-wake cycles incompatible w/ recuperation theories of sleep?

On occasions when subjects stay awake longer than usual, their proceeding sleep time is shorter rather than longer. Because humans and other animals are programmed to have sleep-wake cycles of approx. 24 hours - the more wakefulness there is during a cycle, the less time there is for sleep.

In comparative sleep studies why do we need to be somewhat skeptical?

Only about 60 our of approx. 60,000 vertebrate species have been closely studied for sleep behaviour. Some of those do not meet criteria for sleep at any time (harbour porpoise). Some go for long periods w/o any evidence of sleep (neonatal marine animals e.g. killer whales & migratory birds) or rebounds following such periods. - other researchers dispute that harbour porpoises never sleep.

What are the effects of sleep deprivation on complex cognitive tasks?

Only some cognitive functions are susceptible. Executive function is affected but not logical deduction or critical thinking. Tendency to do risky behaviour - frontal lobes are somehow affected. Certain tests of episodic memory seem to be affected

What do the latest brain imaging studies allow the possibility of in dream research?

Opened the possibility of recording the visual content of a dreamer's dreams while sleeping - Recording brain activity whiles subjects looked and imagined at images, then recorded brain activity while same subjects slept - Computer regenerated subjects' dreams Woke them and asked them to describe their dreams.

What is sleep apnea and who is more susceptible to it?

Patients w/ sleep apnea stop breathing many times each night, then wake up and begin to breathe again and drift back to sleep. Usually leads to a sense of having slept poorly and is thus often diagnosed as insomnia Some patients are unaware of their multiple awakenings and instead complain of excessive sleepiness during the day leading to a diagnosis of hypersomnia More common in males, overweight and elderly

What can happen to these independent structures that normally activate together during sleep deprivation?

Physiological changes that go together to define REM sleep sometimes break apart. E.g. Penile erections which normally happen in REM sleep - begin to occur during slow-wave sleep During total sleep deprivation slow waves which normally occur only during slow-wave sleep begin to occur during wakefulness Suggests REM sleep, slow-wave sleep and wakefulness are not controlled by a single mechanism - but as a result of interaction of several mechanisms that are capable under certain conditions of operating independently of one another.

What EEG signature can be seen in stage 4 sleep?

Predominantly delta waves: large and slowest EEG waves with a frequency of 1-2 Hz

What is the sleep associated with emergent stage 1 EEG called?

REM sleep (high brain activity - levels approach waking levels, energy expenditure, increase in autonomic nervous system activity)

What is the 3rd class of sleep disorders

REM-sleep dysfunction disorders

What is the scanning hypothesis of REM sleep?

Rapid eye movements are the eyes scanning dream scenes rather than random movements (Kleitmen et al.). Concluded that rapid eye movements were a physical marker of dreaming. Studies - woke subjects up during REM to ask them what they were dreaming (self-biased). Approach assumed REM = dreaming, but their initial research confirmed this. (people neglected to report isolated images and thoughts that weren't woven into a narrative). As night progresses narratives present in early REM sleep drop off, and NREM sleep dreams only sometimes have narratives. Today, this is questioned as dreaming is not thought to occur only in REM sleep. 74-80% of REM sleep awakenings led to dream recall 7-9% of NREM-sleep awakenings led to dream recall

What is the carousel apparatus? Describe this sleep deprivation experiment in rats. (Rechtshaffen)

Rats had a yolked control (matched in every area except amt of sleep control subject was getting) - Housed in adjacent chambers on a rotatable disk above shallow pool of water. Disk rotated in both chambers, only when experimental rat fell asleep (EEG sleep signal). - If the sleeping rat doesn't wake immediately and walk in the opposite direction it is shoved into the water. - Experimental rat lost fur shine, increases food intake, but weight still dropped dramatically, died in approx. 12 days. - Experimental rat = 90% sleep deprived. - Control rat = 40% sleep deprived. - Yoked control stayed reasonably healthy. - Upon postmortem examination, the experimental rats had swollen adrenal glands, gastric ulcers and internal bleeding => all stress related illnesses Problem was stress confounded results. Never been replicated in other species. Only study where sleep deprivation has resulted in death.

List the physiological consequences of sleep deprivation

Reduced body temperature Increases in blood pressure Decreases in some aspects of immune function Hormonal changes Metabolic changes

What are some other zeitgebers that can entrain hamsters' circadian cycles without light/dark cycles?

Regular daily bouts of social interactions, hoarding, eating or exercise

What is the evidence that sleep deprivation increases efficiency of sleep?

Sleep deprived subjects have higher proportion of slow-wave sleep (stage 3 & 4), which seems to serve the main restorative function.

Describe the Ralph et al. SCN transplant study in hamsters and results

Removed SCN from fetuses of mutant hamsters w/ abnormally short (20-hr) free-running sleep-wake cycles. Transplanted them into normal adult hamsters whose free-running sleep-wake cycles (25 hrs) had been lesioned. Transplants restored free-running sleep-wake cycles to 20 hour cycles. Transplants in the other direction (from normal hamster fetuses to SCN-lesioned adult mutants had the opposite effect (restored free-running sleep-wake cycles to 25 hrs from the original 20 hr cycle.

Which is more effective polyphasic or monophasic sleep cycles?

Research says that naps have recuperative powers out of proportion with their brevity, suggesting that polyphasic sleep might be more efficient.

Describe the Nykamp et al. study supporting the default theory

Researchers awakened youg adults every time they entered REM sleep, and immediately substituted a 15-min period of wakefulness of reach lost REM period. The participants (unlike controls) were not tired the next day, despite only getting 5 hrs sleep. They displayed no REM rebound Study has been replicated in rats, and is consistent with finding that antidepressants reducing REM sleep are associated with increased awakenings (thus are experiencing a larger proportion of wakefulness because their brain needs to switch out of NREM sleep)

Why is the evidence that REM sleep strengthens memory unconvincing?

Researchers have ignored the null-result studies. Many patients who have taken antidepressant drugs that block REM sleep experience no obvious memory problems (after months/years) Pharmacological blocking of REM sleep in a human study - did not disrupt consolidation of verbal memories, and improved consolidation of motor task memory

What can improve productivity and job satisfaction in shift workers?

Scheduling phase delays rather than phase advances when possible. Shift workers work consecutively later rather than earlier shifts. (because phase delays are easier to adjust to than phase advances)

What cognitive tasks are the most sensitive to effects of sleep deprivation?

Simple, dull, monotonous tasks

What are K complexes?

Single large negative waves (upward deflection) followed immediately by a single large positive wave (downward deflection)

What effects do both jet-lag, and shift work produce?

Sleep disturbances, fatigue, general malaise, deficits on tests of physical and cognitive function that can last for many days.

What are monophasic sleep cycles?

Sleep once a day - adult humans But most adult humans do display polyphasic cycles of sleepiness - usually occuring late in afternoon and late morning

What is one of the most effective treatments for insomnia and how does it work?

Sleep restriction therapy. The amount of time that an insomniac is allowed to spend in bed is substantially reduced Then, after a period of sleep restriction, amt of time spent in bed is gradually increased in small increments as long as sleep latency (time taken to fall asleep) is in normal range. Benefits even severe insomniacs

What 2 EEG signatures can be seen in stage 2 sleep?

Sleep spindles and K complexes

What have sleep deprivation studies assessed

Sleepiness, mood, cognition, motor performance, physiological function and even molecular function

Why are many cases of insomnia iatrogenic?

Sleeping pills - tolerance to hypnotic drugs require greater and greater doses, then patient cannot stop without experiencing withdrawal, which includes insomnia

What are stages 3 & 4 called?

Slow-wave sleep (SWS)

What is the traditional treatment for narcolepsy?

Stimulants (Amphetamines, methylphenidate) - but these have addiction potentials and produce many undesirable side effects - Modafinil - shown to be effective - antidepressants - effective w/ cataplexy

What is sleep deprivation's major confound in Western cultures, lab experiments and animal studies?

Stress - most people who sleep little or irregularly do so because they are under extreme stress - which can have adverse effects independent of any sleep loss Stress can be a contributing factor and many volunteers in deprivation studies find lack of sleep stressful, and many of these studies don't control for stress. - thus tell us little about the function of sleep and how much we need.

What is the nucleus magnocellularis

Structure of the caudal reticular formation that controls muscle relaxation during REM sleep In normal dogs it is active only during REM sleep In narcoleptic dogs - it is also active during catalectic attacks

What is the more recent evidence rapid eye movement scanning the scene within a dream?

Study that was done about 3 or 4 years ago with people with REM sleep behaviour disorder. They act out their dreams. Took EEG, EMG, EOG recordings and video taped subjects sleeping. Had independent observes watch thousands of these videos. All the observers had to agree with what the person was doing. Then looked at their eye movements to see if eye movements would correspond with what would happen in everyday life, that is, it i'm smoking a cigarette are they looking to where the cigarette is, or walking up stairs. Their eyes tracked their own body movements

What is the gene that is mutated in hamsters that have abnormally short 20-hour free-running circadian rhythms?

Tau (2000)

How are our circadian cycles kept on their once-every-24 hr schedule?

Temporal cues in the environment = zeitbergers (e.g. light /dark)

Why is the regular use of antihypnotic drugs risky?

Tend to produce a variety of adverse side effects (e.g. loss of appetite, anxiety, tremor, addiction, disturbance of normal sleep patterns, they may also mask pathology that is causing the excessive sleepiness)

As night progresses how does the pattern change?

Tendency to spend more time in emergent sleep 1 stage, and less time spent in other stages, particularly stage 4. During the night there are also brief periods where person is awake, but they usually do not remember these in the morning

What does the compensatory increase in REM sleep following a period of REM-sleep deprivation suggest?

That REM sleep is regulated separately from the amount of slow-wave sleep - thus REM sleep serves a special function

What is the default theory of REM sleep?

That it is difficult or dangerous to stay continuously in NREM sleep, so brain periodically switches to one of other sleep types including REM (if body has no needs) or awakes (if body has needs - eating, drinking, urination) Thus REM sleep and wakefulness are similar states but REM is more adaptive (maintains alertness to external environment) when there are no immediate bodily needs. - Staying too long in NREM sleep may be bad for brain (associated w/ lack of consciousness and non responsive to external environment) - REM allows breaks from NREM sleep, increases awareness of external stimuli and may work as a transition from deep sleep to REM to wakefulness.

What is the assumption about melatonin & sleep

That melatonin plays a role in promoting sleep or in regulating its timing in mammals

With the exception of loss of muscle tone in core muscles, what do all measures of REM sleep suggest?

That the episodes are emotion-charged

What do the cerveau isolé and encéphale isolé preparations suggest?

That the wakefulness structure was somewhere in the brain stem between these 2 transections.

What do these last 2 findings indicate?

That visual axons critical for entrainment of circadian rhythms branch off from the optic nerve in the area of the optic chiasm which led to discovery of the retinohypothalamic tracts

What do we know about circulating melatonin levels in humans?

The are under control of the suprachiasmatic nuclei with highest levels being associated w/ darkness and sleep

How is the sleep of mammals, birds and humans similar?

characterized by high-amp, low frequency EEG waves punctuated by periods of low-amp, high frequency waves

When dreams were recalled from NREM sleep how did they differ from dreams recalled from REM sleep?

The dreams tended to be isolated experiences e.g. feeling of falling, while REM sleep dreams tended to take the form of stories & narratives

What is the synaptic homeostasis hypothesis?

The fundamental function of sleep is the restoration of synaptic homeostasis which is challenged by synaptic strengthening and synaptogenesis triggered by learning while awake - Slow wave sleep is critical in consolidation - SWS-deprivation in animals has effects on LTP - SWS seems to modulate consolidation (maintenance) - During wakefulness, a building of synapses happens, during SWS there seems to be a pruning back of synapses - thus SWS has a way of reducing/downgrading synapses (ampa receptors decrease in SWS) - Selective - doesn't occur through entire EEG. Greater SWS in ares involved in learning of motor tasks - If you sleep deprive someone after learning a motor task there is still activity in ares of learning

What is the neuropeptide that binds to the receptor protein that is encoded by the narcolepsy-causing gene and how was it discovered?

The gene encodes a receptor protein that binds to a neuropeptide called orexin . Lin et al. isolated the gene in strain of narcoleptic dogs. Orexin neuropeptide exists in 2 forms: Orexin-A and Orexin-B - BUT the concordance rate between identical twins is only about 25%

How do suprachiasmatic nuclei support the idea that this area is a circadian timing mechanism?

The nuclei display circadian cycles of electrical, metabolic, and biochemical activity that can be entrained by the light-dark cycle.

What are the retinohyopthlamic tracts?

The tracts that leave the optic chiasm and project to the adjacent suprachiasmatic nuclei. They mediate the ability of light to entrain photoreceptors.

What is the first mammalian circadian gene to be identified?

clock - mammalian circadian gene discovered in mice (1997)

What happens to EEG voltage as person progresses from stage 1 sleep thru stages 2, 3 and 4?

There is a gradual increase in EEG voltage and decrease in EEG frequency - stage 2 has higher amp and lower frequency than stage 1 EEG

What are the results of a meta-analysis on consumption of exogenous melatonin?

There is a small but significant soporific effect

Why aren't cones & rods necessary for entrainment of photoreceptors by light?

These photoreceptors are a rare type of retinal ganglion cell with distinctive functional properties. During the course of evolution these photoreceptors have sacrificed the ability to respond quickly and briefly to rapidly to light changes and instead favour the ability to respond consistently to slowly changing background illumination levels

How do these 3 classes of antihypnotic drugs promote wakefulness?

They boost the activity of catecholamines (norepinephrine, epinephrine and dopamine) by increasing their release into synapses, blocking their reuptake from synapses or both. Antihypnotic mechanisms of 2 other stimulant drugs: codeine and modafinl are less understood

Who was Randy Gardner and what did he attempt to do?

Tried to break the previous world record of 260 hours of consecutive wakefulness. Didn't sleep for 264 hrs. 12mins. Mixed reports of his symptoms

Why does the increase in efficiency of sleep in sleep deprived individuals make conventional sleep deprivation studies useless?

True need for sleep can only be assessed by experiments in which sleep is regularly reduced for many weeks to give participants the opportunity to adapt to getting less sleep by maximizing their sleep efficiency. Only when people are sleeping at maximum efficiency can researchers determine how much sleep they really need. This reflects the plasticity and adaptiveness of the adult mammalian brain.

What happens when sleepers were woken in the middle of REM episodes?

Vivid recall of dreams. I0% of awakenings from REM sleep but only 7% of awakenings from NREM sleep led to dream recall.

What are the 6 stages of sleep called?

Wakefulness: Rapid low voltage EEG (shallow) Alpha: Transition = Just before sleep (w/ alpha waves) Associated w/ Hypnagosia (hallucinations, dreamlike, falling, twitching) Theta: Stage 1 sleep - slower signal than alert wakefulness & appearance of theta waves Theta waves also appear during meditation (used to judge effectiveness of meditator) Delta: SWS: Stage 3 & 4 stages - slowest and largest waves Stage 4 has more Delta waves than stage 3 (old method) Beta: Wakefulness - Active/busy Gamma: Natural oscillation -> conscious perception (?) Mu: Sensory motor rhythms (over motor areas) Mu

How do patterns of sleep cycles change over the course of a lifetime?

We first see evidence of sleep in the womb => large % of REM (thus this may reflect the importance of REM for early development) There is a drop off of REM sleep duration after teenage years which gradually continues to decline as we age.

How does REM occur?

When a network of independent structures become active together

What is Internal desynchronization, and what 2 points does it suggest?

When sleep-wake and body temperature cycles break away from one another E.g. In one study, free-running periods of both sleep-wake and body temperature cycles were initially 25.7 hours, then they broke away from each other with the sleep-wake cycle increasing to 33.4 hrs, and body temp cycle decreasing to 25.1 hrs. 1. This suggests that there is more than one circadian timing mechanism 2. Sleep is not causally related to decreases in body temperature that are normally associated with it.

What are lucid dreams?

When you have varying control over content in dreams - akin to being awake. Dreamer is aware that they are dreaming and they can affect the course of the dream. Studied self-reported lucid dreamers, gave the instructions before they went to sleep (draw triangle w/ arm or do a specific eye movement) Then wired them up and tested them to see if they carried out his instructions in their sleep. They did. Lucid dreams involve more frontal lobe activity, more comparable to awakened state in brain activity. Lucid dreams have contributed to our understanding of dream content. Some lucid dreamers report being unable to focus on find grained visual details of certain items. They even have glasses that are supposed to help you lucid dream (flash when you're in REM sleep, thus you can start to take control of your dream) success rate is very low.

How does Jet-lag occur

When zeitgebers that control phases of various circadian rhythms are accelerated during east-bound flights (phase advances - harder to adjust to), and decelerated during west-bound flights (phase delays - easier to adjust to). Can last for a long time (10 days for 10.5 hour phase advance)

What are the other physiological signs of REM sleep (aside from REMs, loss of core muscle tone and low-amp, high freq. EEG)?

a) Cerebral activity (oxygen consumption, blood flow & neural firing) b) Increase to waking levels in many brain structures, c) Increase in variability of autonomic nervous system activity (blood pressure, pulse, respiration etc.) d) Clitoral/penal erections common

What happened when Bremer introduced strong visual or olfactory stimuli to cats with cerveau isolé?

high-amp, slow wave activity (sleep) would change to a desynchronized EEG (low amp, high freq EEG) but this arousing effect barely outlasted the stimuli

What are polyphasic sleep cycles?

regular sleeps more than once per day - most mammals and human infants

What does this evidence challenge

the widely held belief that humans have a fundamental need for at least 8 hours of sleep per night.

What did Freud believe dreams were triggered by

unacceptable repressed wishes, often of a sexual nature

What does the posterior hypothalamus promote?

wakefulness

Do most mammals and birds sleep?

yes

Is narcolepsy a REM-sleep-related disorder?

yes, but usually categorized as a hypersomnic disorder