Chapter 9 - Sleep and Biological Rhythms

**Stages of Sleep** (See slide 13)

**Stage of Sleep**

Stage 4

-12-15% -very deep sleep -rhythmic breathing -limited muscle activity -EEG shows mostly delta waves *more 50% delta waves

REM

-20-25% -dreaming occurs -muscles are inhibited -heart rate increases, and breathing is rapid and shallow -EEG shows fast waves

Stage 3

-4-6% -Deep sleep begins -EEG shows some delta waves *less than 50% delta waves

Stage 2

-44-55% -slightly deeper sleep. -breathing pattern and heart rate slow down -EEG shows sleep spindles and k-complexes

**Control of components of REM sleep**

-ACh neuron in pons - gential activity -Reticular Formation - ACh neurons in forebrain & pon - cortical activity -inhibitory interneurons in SC inhibit motor neurons which inhibits movements (if rem sleep disorder is present, inhibitory interneurons are not present so you are not paralyzed)

Sleep Deprivation

-Chronic sleep deprivation is a contributing factor to: Obesity Hypertension Irritability Poor decision making Cognitive impairment Loss of concentration and creativity

Muscle activity

less movement, muscle paralysis during REM sleep

Allostatic

regulated by hormonal and nerual responses to stress

Circadian

regulated by light/dark cycle

What does an EEG measure

sets of action potential

Suprachiasmatic Nucleus (SCN)

Primary biological clock located in hypothalamus Receives input from retinal ganglion cells that contain melanopsin Sends output to VLPO, orexin neurons and pineal gland

Sleep

Reduces alertness, awareness, and perception of events occurring around us.

Homeostatic

Regulated by adenosine

What causes your sleep deprivation?

Stress Caffeine and alcohol Undiagnosed medical conditions Medicines, vitamins, supplements Pain Being exhausted, but not sleep Irregular sleep schedule

Two types of sleep (How to tell with eeg, eog, emg) ^see slide 12^

The EMG is the tell. It will be flat during REM and has highest activity during wake.

**Treatments for Sleep Deprivation**

Tips to Improve Your Sleep Avoid caffeine, alcohol, nicotine, and other chemicals that interfere with sleep Turn your bedroom into a sleep-inducing environment Establish a soothing pre-sleep routine Go to sleep when you're truly tired Don't be a nighttime clock-watcher Use light to your advantage Keep your internal clock set with a consistent sleep schedule Nap early - or not at all Balance meals and fluid intake Exercise early

. Human narcolepsy a. can be treated using sleep-inducing drugs. b. involves an absence of orexin from CSF in most narcoleptics. c. involves the intrusion of slow-wave sleep components into the awake state. d. is a psychological disorder. e. is treated using lithium salts.

b

**Specific brain areas keep us awake and others areas put us to sleep**

-Hypothalamus = Sleep = Ventrolateral preoptic area (VLPO) (GABA - inhibits) -Areas in the brainstem = awake =arousal neruons

**How does neural activity affect an EEG?**

-Irregular firing: increased frequency/decreased amplitude (awake) -Synchronized firing: decreased frequency/increased amplitude (asleep) ^High frequency and amplitude = epilepsy

Biological clock disorders

-Jet Lag -Seasonal Affective Disorder -Monday Morning Blues

Purpose of Sleep

-NREM helps with declarative learning -REM helps with non-declarative learning -If you aren't getting enough REM, it will start occurring earlier in the night.

REM

-Sleep Stages = 5 -heart rate, respiration, blood pressure = variable -dreaming = most dreaming, vivid

The stages occurs in cycle throughout the night

-deep sleep happens within the first three hours -REM happens closer to waking -REM increases throughout the night while deep sleep decreases -Cycle is about 90 minutes

Treatments for Narcolepsy

-drug stimulants = ritalin (stronger than coffee) -Behavioral remedies =Maintain regular sleep schedule/ Schedule naps during the day/ Avoid heavy meals and alcohol/ Do not drive or operate machinery when feeling sleepy

**Adenosine**

-high level before sleep -low level after waking up -Caffeine = antagonist - evens out VLPO and Arousal neurons -because VLPO is inhibited, Arousal neurons are more active.

**Orexin** (dinosaur)

-in hypothalamus - keeps us awake -activates arousal neurons -light/emotional state/energy balance/metabolic cues affect orexin release -no orexin = arousal neurons off = VLPO on = falling asleep -Orexin knockout = straight to REM

Stage 1

-only 4-5% of sleep -light sleep -muscle activity slows down -occasional muscle twitiching

**Control of REM flip-flop switch*

-orexin excites arousal neurons and vlPAG -VLPO inhibits vlPAG -which is why when there is no orexin, skeeter goes straight to REM (emotional stimuli turned on SLD)

Non Rapid Eye Movement (NREM) Sleep

-sleep stages = 1-4 -heart rate, respiration, blood pressure = decreased -dreaming = rare, thought-like

**VLPO and Arousal Neurons**

-they talk to each other - when one is active, it inhibits the other -flip flop switch

Control of REM sleep

-vlPAG (vegan pig) (ventrolateral periaqueductal grey matter of the midbrain) = REM off -SLD (slide into rem sleep) (sublaterodorsal nucleus of pons) = REM-On -they inhibit each other

**But how is the transition from sleep to wake controlled**

-what makes sleepy/tired = dark, just ate, relaxed what makes awake = light, just slept, stress -Neurons sensitive to these signals, particularly light and dark, switch the "wake up" and "go to sleep" areas on and off.

Given what you know about the control of our sleep-wake circuit, design a therapy to help those who have difficulty sleeping. In your answer, be sure to describe how this therapy would act on the neural pathways controlling our sleep-wake cycles.

...I would start by putting the patient in a dark relaxing room, this will help inhibit the orexin neurons. With the orexin neurons inhibited, which will inhibit the arousal neurons. With the arousal neurons inhibited, the ventral lateral preoptic area (VLPO) will then activate. I would then administer a low-dose of serotonin (5-HT) and norapenphren (NE) antagonist to help inhibit the vlPAG. With the ventrolateral periaquaductal grey matter of the midbrain inhibited, the sublaterodorsal nucleus of the pons (SLD) will then be able to activate. This will allow the patient to enter REM sleep. Drugs would only be a beginning step, behavioral therapy would be the next step. However, the patient needs to establish a normal sleep cycle first. Would teach the patient relaxing pre-bed-time routines that would be conducive for the patient to fall asleep. The patient would be monitored for side-effects such as suicidal thoughts since 5-HT is responsible for mood also, and would only be on the drugs for a short period of time.

**Additional control of REM flip-flop switch**

5-HT (saratonin) -Raphe Nuclei NE (noraporpherin) -locus coeruleus (our pornographer stimulates vlPAG so we don't sleep/go to REM Sleep)

Biological Clocks

Circadian rhythms Daily rhythmical change in behavior or physiological process (~25 hr cycle) Some behaviors are responsive to changes in light, but others are responsive to endogenous clock Examples: Sleep-wake cycles, body temperature, thirst, appetite, and pain sensitivity

Control of Sleep-Wake Cycle

Control of Sleep-Wake Cycle

Sleep Apnea

Disorder involving patterns of sleep, usually short, during which breathing stops entirely. Affects 12 million Americans, occurring most among men over the age of 40 who are overweight. Suspected as a cause of Sudden Infant Death Syndrome (SIDS) Many cases can be treated by clearing airway.

Sleepwalking

Disorder that occurs when people walk or do other activities while they are asleep. Occurs during slow-wave sleep (stage 3 or 4), so it tends to occur early in the night. Can occur at any age, but most common in children ages 5-12. Causes are usually unknown, but fatigue, lack of sleep and anxiety are all associated, and it appears to run in families.

Devices to measure sleep

Electromyogram (EMG) -muscle movement Electrooculogram (EOG) - eye movement Electroencephalogragh (EEG)- brain waves (cap on head/ left = odd, right = even, letters= area)

Control of Sleep-Wake Cycles

Homeostatic Regulated by adenosine Allostatic Regulated by hormonal and neural responses to stress Circadian Regulated by light/dark cycle

**How is being asleep different from being awake?**

How is being asleep different from being awake?

Insomnia

Inability to fall asleep or stay asleep Affects 25% of the population occasionally, and 9% regularly. Affects women more commonly than men, elderly more commonly then young adults. Medications seldom work for long term treatment, although behavioral treatments can be effective.

Two types of Sleep

Two Types of Sleep

Brain Activity

Unconscious, dreaming, changes in patterns of measured activity

**The EEG detects multiple stages of sleep**

^see slide 10 and 11 for picture^

. The "on" portion of the flip-flop mechanism for REM sleep is located within the a. dorsal pons. b. occipital cortex. c. suprachiasmatic nucleus. d. globus pallidus. e. preoptic area.

a

10. The "ticking" of a clock cell within the SCN appears to involve a. feedback loops of intracellular protein production. b. the rhythmic opening of sodium channels in the membrane. c. interactions between two adjacent clock cells. d. the rhythmic opening of calcium channels in the membrane. e. the buildup of sodium in the clock cell over time.

a

2. You are watching the sleep record of a person whose record contains 85% delta wave activity. Your best guess is that this person is a. in stage 4 of slow-wave sleep. b. dreaming. c. in stage 1 of slow-wave sleep. d. making the transition from wakefulness to sleep. e. awake.

a

8. Circadian rhythms are a. endogenous cycles of activity over the course of a day. b. not found in plants. c. learned patterns of daily activity. d. annual changes in behavior (such as migration). e. monthly cycles of reproductive activity.

a

. The primary function of slow-wave sleep is to a. clear brain waste products produced by REM sleep. b. promote dreaming. c. rest the brain. d. promote brain development. e. facilitate learning.

c

1. The various stages of sleep are easily distinguished by a. visible changes in respiration. b. changes in motor movements involving speech. c. changes in the electrical activity of the brain. d. changes in consciousness. e. the quality and quantity of dreams.

c

3. Which of the following is true of human sleep cycles? a. Sleep cycles are random across the night. b. Subjects first enter REM sleep and then transition to non-REM sleep. c. As the night goes on, the relative length of REM sleep increases in each successive cycle. d. Stages 3 and 4 of slow-wave sleep mostly occur in the early morning hours. e. Each non-REM/REM cycle lasts about 45 minutes.

c

**How is the activity of the SCN controlled?**

clock genes produces clock protein which then inhibits clock genes which will stop making clock protein which will stop inhibiting the clock gene which then will start producing clock proteins ^THIS IS FEEDBACK INHIBITION^

6. Deprivation of REM sleep on one night results in an elevated amount of REM sleep on the following night. This rebound phenomenon suggests that a. emotional well-being requires slow-wave sleep. b. REM sleep functions to rest the brain. c. there is a physiological need for stage 1 slow-wave sleep. d. there is a physiological need for a certain amount of REM sleep. e. the brain does not regulate REM sleep.

d

9. Which of the following is true of melanopsin? a. Melanopsin is found within rods but not cones. b. Melanopsin is found within cones but not rods. c. Melanopsin activity is suppressed by light. d. Melanopsin is found within ganglion cells. e. Melanopsin in rods is a cue that resets SCN clock cells.

d

Other body functions

decreased metabolic activity, lower body temperature, decreased heart rate and blood pressure