4 - Sleep Physiology

Question 1

How long do most people need to sleep?

Answer 1

7-8 hrs

Question 2

Familial Insomnia

Answer 2

Plaques and thalamus degenerates

Lose ability to nap, then sleep

Death within one year

Question 3

***Circadian Cycle***

Depends on?

Key Receptors/Pathway?

Answer 3

Presence of light

Retinal Ganglion Cells detect light, send info along retinohypothalamic tract, projects to Suprachiasmatic Nucleus (SCN) of Anterior Hypothalamus

Question 4

What is the key structure for controling circadian rhythm of sleep-wake cycle?

Answer 4

Suprachiasmatic Nucleus (SCN)

Question 5

What is the key hormone for regulating sleep?

Where is it produced?

Answer 5

Melatonin

Produced in Pineal Gland

Synthesis increases and light decreases

Question 6

Alerting Signals

Major component of sleep load?

Answer 6

Generated by the SCN

Alerting Signals counters the sleep load‘built’ throughout the day

Adenosine major component of sleep load

Question 7

Four Stages of Sleep (defined by EEG)

Answer 7

Stage 1 - N1/S1

Stage 2 - N2/S2

Stafe 3 - N3/S3

REM

Question 8

Answer 8

Question 9

What stage are sleep spindles found in, and what is their importance?

What other patterns are found here?

Answer 9

Stage 2

Important for consolidation of motor skill memory in young adults

- - -

K-Complex (higher amplitude)

Question 10

Stage 3 sleep characteristics

Answer 10

Slow Wave Sleep

Deepest level of sleep; Delta waves

Hard to wake people up

Question 11

Physiological Changes in NREM sleep?

Answer 11

Decrease muscle tone, heart rate, bp, body temp

Can still move

Sleep walk/talk

Question 12

REM Sleep

Physiological changes?

Dreams?

Infants vs Adults

Answer 12

“Paradoxical” - Brain as active as when awake

Increase in BP, hr, metabolism

Paralysis of large muscles (not diaphragm)

Penile erection

MOST dreams occur during REM Sleep

Infants spend more time than adults

Question 13

REM Rebound

Answer 13

If deprived, can go directly into REM sleep at next opportunity

Question 14

Cycles of REM / NREM sleep?

Answer 14

After REM, brain cycles back through NREM

N3 occurs in 2nd cycle, not again

REM occurs ~ 90 minutes; duration increases with each cycle

Question 15

Autonomic Activity in Sleep

REM vs NREM

Answer 15

REM - Sympathetic (erection)

NREM - Parasympathetic

Question 16

What is a major characteristic of Stage 3 Sleep?

Answer 16

Low frequency, high amplitude EEG waves

Question 17

Neural Circuit Governing Sleep?

Neurotransmitter/Location?

What is the counter area that will put you to sleep?

Answer 17

Reticular Activating System (RAS) = awake

Cholinergic near Pons/Midbrain Junction

Thalamus = sleep

Question 18

What role does the Thalamus play in sleep?

Answer 18

Stimulation causes sleep

Gates sensory information, blocks input during sleep

Question 19

Neurotransmitters:

Wakefullness

vs

Sleep

Answer 19

Wakefullness:

1. Monoamines (dopamine, norepinephrine, serotonin)
2. Acetylcholine
3. Histamine (antihistamines block, make you sleepy)
4. Orexin/Hypocretin

Sleep:

1. Adenosine
2. GABA
3. Melatonin
4. Galanin

Question 20

VLPO

Answer 20

Ventrolateral Preoptic Nucleus

Sleep State; inhibit neurons responsible for wakefullness

Question 21

Clinical: Insomnia

Answer 21

Cause: Stress, Anxiety, caffeine (adenosine), depression, medication

Question 22

Clinical: Obstructive Sleep Apnea

Answer 22

Interupted breathing caused by partial or complete blockage of upper airway (loud snoring)

Wake up often, increased bp, obesity

CPAP machine treatment

Question 23

Clinical: SIDS

Answer 23

Infants unable to arouse from SWS

Immature breathing control system may fail

Infants should sleep on their backs

(could be related to sleep apnea)

Question 24

Clinical: Restless Legs Syndrome

Answer 24

Discomfort in legs at night

Helped by moveing legs

Middle-aged to older adults

Question 25

Clinical: Narcolepsy

Answer 25

Excessive daytime sleepiness; may go directly into REM sleep

Defect in Orexin/Hypocretin-synthesizing Neurons

Lose muscle control (cataplexy) during episodes of emotion–fall down and immediately sleep

Question 26

Clinical: REM Sleep Behavior Disorder (RBD)

Answer 26

Affected individuals can fight during sleep; mostly men over 50

Brainstem disorder; increased incidence of Parkinson’s

Question 27

Sleep and Aging

Answer 27

Older = lighter, shorter times

Older = less SWS, less sleep spindles

Older = wake up frequently

Older = less melatonin

Older = less VLPO