1. Swetha Rao
Sleep

2. Why is sleep important? We sleep for nearly 1/3 of our lives
Concentration, Memory, and Coordination
Sleep Loss = Alcohol
Lack of sleep can increase risk of diabetes, cardiovascular disease and heart attacks, stroke, depression, high blood pressure, obesity, and infections
Sleep Disorders affect up to 70 million people

3. Slow Wave Sleep First hour or so brain waves slow down
relaxation of the muscles and the eyes
Heart rate, blood pressure, and body temperature all fall
If awakened, most people recall only fragmented thoughts, not an active dream

4. REM Sleep Rapid Eye Movement
Next half hour or so, neocortical EEG waves become similar to waking
Atonia: paralysis of the body’s muscles (only the muscles that allow breathing and control eye movements remain active)
Active dreaming
Heart rate, blood pressure, and body temperature become much more variable
Men often have erections
First REM period usually lasts 10 to 15 minutes.

5. Stages of Sleep

6. Insomnia Initially or partway awakening
Short-acting sedatives and sedating antidepressant drugs suppress deeper stages of slow wave sleep

7. Obstructive Sleep Apnea
Deeper sleep = Airway muscles collapse and close airway
Can’t enter deeper stages of slow wave sleep
High blood pressure, increased risk of heart attack, increased risk of automobile accidents,
Treatments to reduce airway collapse: lose weight, avoid alcohol and sedating drugs, avoid sleeping on back
Devices that induce continuous positive airway pressure

8. Muscles fail to become paralyzed
Periodic Limb Movements
Intermittent jerks of legs and arms as entering slow wave sleep
REM Behavioral Disorder
Muscles fail to become paralyzed
Act out dreams
Common in Parkinson’s patients
Treated with: benzodiazepine (clonazepam)

9. Narcolepsy Switching mechanisms don’t work properly
Loss of nerve cells in the lateral hypothalamus which contains the neurotransmitter orexin
Narcoleptic Dog: WTwI

10. Sudden Sleep Attacks during the day
Hypnagogic Hallucination: Enter REM sleep and dreaming state while still partially awake
Cataplexy: Attacks of paralysis triggered by emotional experience

11. Sleep Regulation: AWAKE
Acetylcholine and Monoamines (norepinephrine, serotonin, dopamine, and histamine)

12. REM sleep:
Cholinergic nerve cells send signals to activate the thalamus
EEG similar to wakefulness
Monoamine pathway is quiet
Perceived as a dream

13. Waking Up Two groups of nerve cells in hypothalamus
Ventrolateral preoptic nucleus:
GABA and galanin
When they fire, they turn off arousal system and cause sleep
Damage = irreversible insomnia
Neurotransmitter orexin:
Excitatory signal to monoamine neurons
Orexin levels in patients with narcolepsy are abnormally low

14. Need for Sleep: Homeostasis
Body’s need to seek a natural equilibrium
Adenosine (chemical)
increases in the brain during prolonged wakefulness
levels modulate homeostasis
Caffeine acts as an adenosine blocker

15. Circadian Timing System
Suprachiasmatic nucleus: group of nerve cells in hypothalamus that acts as a master clock
Cells express clock proteins which go through biochemical cycle of 24 hrs
Receives input from retina so can be reset by light

16. Suprachiasmatic nucleus Subparaventricular nucleus
Dorsomedial nucleus of hypothalamas
Ventrolateral proptic nucleus (orexin)
Regulate sleep and arousal