Unit 2: Chapter 9

Identify and briefly describe three physiological measures used to characterize sleep and arousal states.

- Electroencephalogram (EEG) + Brain waves from scalp surface - Electrooculogram (EOG) + Eye movements - Electromyogram (EMG) + Muscle tone

Define the following terms: entrainment, zeitgeber, free-running rhythm.

- Entrainment: The process of the rhythm becoming set by a stimulus (i.e., a zeitgeber). - Zeitgeber: Cue about time of day (e.g., presence or absence of sunlight, alarm clocks). - Free-running rhythm: Duration of this rhythm of sleep (typically 25 hours).

Name four brain wave patterns identified through EEG recordings and briefly differentiate them with respect to amplitude and frequency. Indicate during which sleep stages and wakeful states each brain wave form is typically observed.

- Alpha activity + EEG wakefulness waves + Awake and initial Stage 1 + Regular medium frequency waves (8-12 Hz) + Generally associated with a state of relaxation; resting quietly, but awake - Beta activity + EEG wakefulness waves + Awake and REM sleep + irregular low amplitude, high frequency waves (13-30 Hz) + Indicative of alert and vigilant activity; generally associated with a state of arousal - Theta activity + EEG slow wave sleep + Stage 1 and REM sleep + occurs intermittently during early stages of slow wave sleep and REM sleep (3.5-7.5 Hz) - Delta activity + EEG slow wave sleep + Stage 3 and Stage 4 + Regular, synchronous electrical activity of less than 4 Hz

List examples of drugs that promote sleep and briefly describe their mechanisms of action.

- Ambien (zolpidem) is a non-benzodiazepine that is used with the idea that it reduces the 'hangover effect' that commonly occurs with the use of benzos + orexin antagonist - Belsomra is an orexin antagonist on orexin receptors. - Xanax (niravam) is a benzo that tends to be preferred as a sedative because it is eliminated quickly. + Benzos work on the benzo agonist receptor sites + For GABA, GABA A ionotropic receptors, action produces sedation and reduces anxiety/fear. In the brainstem, it suppresses motor neuron control of muscles

Briefly describe the circuit that Carlson refers to as the "flip-flop".

- At least four main brainstem arousal systems - mutual inhibition of the sleep neurons in the preoptic area and the regions they inhibit establish periods of sleep and waking. - Either sleep neurons are active and inhibit the wakefulness neurons, or vis versa. Impossible to have both sets be active at the same time. - Flip-flop has important advantage: when it switches, it does so quickly; no in-between state - Orexinergic neurons help stabilize the sleep/waking flip-flop through their excitatory connections to the wakefulness neurons

Describe blood flow changes observed in the brain during REM sleep and briefly discuss the implications of these findings.

- Cerebral blood flow and oxygen consumption are accelerated during REM sleep - Blood flow high in visual association cortex (visual hallucinations that occur during dreams), but low in primary visual cortex (bc of lack of activity; eyes not receiving visual input)

Define insomnia and discuss some of its causes.

- Characterized as difficulty falling asleep after going to bed or after awakening during the night - Symptom, not a disease - Causes, often iatrogenic + Tolerance to sedative-hypnotic drugs + Frequent symptom of depression + Other causes: sleep apnea, nocturnal myoclonus (PLMD), restless legs

Define circadian rhythm and list examples of circadian rhythms.

- Daily rhythmical change in behavior or physiological process - Sleep-wake cycle + Our sleep-wake cycle is entrained by cues in the environment - when lights come on, we are more active, when they are not, we go to sleep. + Wheel running is an objective way to measure activity, can have that wheel connected to a chart recorder. The animal will engage in more activity when the lights are on and will engage in less activity when the lights are off. > When the lights come on and when they go off are influencing the activity in the animals. - body-temperature cycle

Identify and characterize the stages of sleep with respect to at least three physiological measures.

- EEG + Wakefulness and Slow wave sleep - EOG + Rapid eye movement in REM - EMG + Paralyzed in REM + Changes as we progress through different stages of sleep + Loss of muscle tone + Muscle twitches in Stage 1

Discuss the role of glycogen and adenosine in the chemical regulation of sleep and wakefulness.

- Glycogen: Stored energy; in times of increased brain activity, it is converted to fuel for neurons - Adenosine: Neuromodulator released by astrocytes, important to the initiation of sleep (promotes sleepiness). + Caffeine = Adenosine receptor antagonist.

Identify and briefly summarize three physiological processes that contribute to the regulation of sleep.

- Homeostatic: The longer you go without sleep, the longer your body tries to counteract that and 'make up the debt' - Allostatic: External forces that help fight to urge to sleep and stay awake longer; reaction to stressful events in the environment - Circadian: Circadian patterns in the sleep of at least mammals and birds; animals that are homeothermic. Regulatory mechanisms that determine when we sleep in addition to the fact that there are mechanisms that make sure we sleep at some point (also involves the hypothalamus). + Most mammals' circadian rhythms are a little bit longer than our day. Regulation of sleep and arousal is not left up to a simple on-off mechanism. Multiple pathways contributing to our level of arousal that vary over time. There are also mechanisms in our environment that alter when we sleep.

Summarize and discuss the findings from Horne's review of research and differentiate between the physical and cognitive effects of sleep deprivation.

- Horne reviewed sleep deprivation experiments. Found most did not find interference with physical exercise, and no evidence of a physiological stress response; primary role of sleep does not seem to rest and recuperation of body, but of brain - mental restoration; change in amount of slow wave sleep when individual engaged in a lot of mental activities, less change if it's physical activity

Characterize the typical effects of sleep deprivation.

- In non-humans, it is hard to tease out sleep-loss from stress. Keeping animals awake is stressful. - Hooked EEG recording up to an animal and attempted to control for stress. Carousel apparatus with yoked controls. Control could sleep, but if experimental animals tried to sleep, both would drop into water. Experimental animals died within days, while controls remained relatively healthy. - Human research: Can't ask people to do this. - Sleep recovery: Randy Garnder stayed awake for 11 days (264 hours); not a scientific study, no pre-measures, etc. Recorded sleep AFTER by scientists. Slow wave and REM sleep are particularly important. We can never make up all the sleep we lose, but we do make it up at different stages. - There is a natural circadian rhythm to our bodies - "daytime" cues alertness; much harder to fight off sleep at nighttime. - Don't have results from total sleep deprivation for more than a day. 24-48 hours sleep deprivation: looking at link to depression. Very immediate antidepressant effects for some people with depression. For the purpose of studying the function of sleep: Typically short-term, not motor control/motor tasks, but mental and cognitive impairments. Hallucinations, struggle concentrating, especially on complex tasks, sustained attention, mood changes and irritability.

Identify the drugs currently available to treat narcolepsy and briefly describe their mechanisms of action.

- Modafinil + Dopamine reuptake inhibitor + Increases activity of orexin - Sodium oxybate (GHP) + Both schedule 1 and 3 drug + Quick sedation + Too sudden of onset for insomnia +Not as long acting as benzo + Reduces cataplaxy > If they take it to sleep at night, daytime cataplexy during day is reduced - Could be prescribed modafinal during the day and sodium oxybate at night

Identify and characterize the symptoms of at least two sleep disorders, including the stages of sleep typically involved in each disorder.

- Periodic Leg Movement Disorder + Difficulty sleeping through night and excessive daytime sleepiness + Involuntary leg movements during sleep, occur at periodic intervals, without awareness during non-REM sleep + Difficulty sleeping through night and excessive daytime sleepiness - Narcolepsy + Sleep attack (5-30 minutes) + Cataplexy - sudden paralysis of muscles while awake. Frequently brought on by intense emotions + Immediate REM at sleep onset + Sleep paralysis + Hypnogogic hallucinations - experiencing dream-like state while awake

Identify two common examples of disruptions to circadian rhythms. Summarize behavioral approaches to reduce these disturbances.

- Phase advanced acceleration of circadian rhythm (a backward shift in sleep. wake cycle, east to west travel). - Phase delays deceleration of circadian rhythms (west to east travel) + Can adjust more quickly to these than phase advances - Behavioral approaches: black out shades, light boxes, taking melatonin, sleep hygiene

Summarize and discuss research findings regarding the effects of REM sleep deprivation.

- Rebound phenomenon: The increased frequency or intensity of a phenomenon after it has temporarily suppressed; for example, the increase in REM sleep seen after a period of REM sleep deprivation. Greater than normal percentage of recovery of REM sleep, suggesting there is a need for a certain amount of REM sleep. - REM deprivation has antidepressant effects - REM deprivation can produce cognitive/memory deficits

Name five brain regions and associated neurotransmitters involved in the regulation of sleep and wakefulness.

- Serotonin + raphe nuclei + Show different levels of firing as we progress through different stages of sleep; they are more active when we are awake. Raphe serotonergic neurons are active during REM sleep. - Norepinephrine + locus coeruleus + Part of the arousal system, these neurons are active when we are awake, and when we are sleeping these neurons are silent. - Acetylcholine + pons, basal forebrain + Important for cortical desynchronization - Histamine + Tuberomammillary nuclei + Histamine neurons are active during waking and not so active during slow wave sleep and REM - Orexin + Lateral hypothalamus + As far as we know, it is only found in the lateral hypothalamus. Orexin has an excitatory effect. Neurons fired at high rates in rats during alert or active waking and low rate during quiet waking, SWS, and REM sleep. Highest rate of firing seen when rats engaged in exploratory activity (e.g., food seeking behavior).

Summarize at least two theoretical perspectives regarding the reasons for sleep.

- Sleep as a restorative process + Human brain comprises 2% of total body weight, but expands 20% of the body's energy during quiet wakefulness + Cerebral metabolic rate and blood flow decline during slow-wave sleep to about 75% of the waking level during stage 4 sleep + Regions that have the highest levels of activity during waking show the highest levels of delta waves - and the lowest levels of metabolic activity - during slow-wave sleep - Sleep as an adaptive function + The lengths of time and when animals sleep depends on predator avoidance and energy conservation + Result of sleep as a natural selection + Only mammals and birds engage in REM sleep

Identify the hypothalamic nucleus known to regulate circadian timing of the sleep-wake cycle.

- suprachiasmatic nucleus (SCN): A nucleus situated atop the optic chiasm. It contains a biological clock that is responsible for organizing many of the body's circadian rhythms.