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Neuro II > Physiology of Sleep > Flashcards

Physiology of Sleep Flashcards

1
Q

What is the overall definition of sleep? Neuroscience definition?

A

temporary state of unconsciousness from which one can awaken when stimulated

Neuro: dynamic state of shifting electrical activity & flow of chemicals

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2
Q

What is a sleep study?

A

polysonnography

EEG: electroencephalogram

EMG: electromyogram

EOG: electrooculogram

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3
Q

What are the stages of a sleep cycle? How long are each cycle? How many sleep cycles does a typical adult have / night?

A

A. Non-Rapid Eye Movement sleep (75%)

B: Rapid Eye Movement sleep (25%)

whole cycle ~90 minutes & have ~5 cycles /night

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4
Q

What is the trend for percentage of time spent in the different phases of the sleep cycle as we age?

A

babies → ~ 85% REM

adults → ~25% REM

% time spent in REM decreases as we age

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5
Q

What are the 5 basic steps to the sleep cycle?

A
  1. Awake
  2. N1: transition
  3. N2: light sleep
  4. N3: deep sleep
  5. REM sleep

notice that in the beginning, the length of time spent in N3 is the largest & the length of time spent in REM increases toward the end

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6
Q

The first half of sleep is considered what type of sleep?

The second half is considered what type of sleep?

A

First half: deep sleep

Second half: REM sleep

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7
Q

What types of waves are seen seen in each stage of sleep?

A
  • Awake (alert) : Beta
  • Awake (relaxed) : alpha
  • N1 (drowsiness) : theta
  • N2 (light sleep): theta
  • N3 (deep sleep) : delta
  • REM : Beta
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8
Q

What neurotransmitters are responsible for the different waves seen in different levels of sleep?

A
  • Awake (eyes open) : Beta → increased norepinephrine
  • Awake (eyes closed) : alpha → increased histamine
  • N1, N2, N3 : theta & delta → increased GABA
  • REM : beta → increased GABA + ACh
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9
Q

What are the characteristics of REM sleep?

A

saw-tooth wave & PGO activity

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10
Q

Fill out the trends indicated by the black bocks in the provided table:

A
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11
Q

What is the sleep center of the brain & what is the main “switch”?

A

hypothalamus

Ventrolateral preoptic nucleus (VLPO)

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12
Q

What is the mechanism of sleep induction by adenosine?

A
  • Adenosine binds to the A1 & A2 receptors on the VLPO of the hypothalamus
  • this activates the VLPO → secretes GABA → promotes sleep
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13
Q

How does caffeine inhibit sleep?

A

Caffeine binds to & blocks the A1 & A2 receptors on the VLPO

VLPO is inhibited from producing GABA

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14
Q

Why do we build up adenosine during the day?

A

ATP use

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15
Q

Increased levels of what substance in the forebrain promotes sleep?

A

adenosine

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16
Q

What are the nuclei in the hypothalamus that are related to sleep & wakefulness? Actions of each?

A
  • VLPO → GABA secretion (induce sleepiness)
  • SCN → stimulated by light (help you wake up)
    • during sleep, produces melatonin (keep you asleep)
  • Lateral Hypothalamus → orexin (keep you awake)
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17
Q

Lesion in the lateral hypothalamus can lead to what condition?

A

narcolepsy

d/t loss of orexin neurons

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18
Q

What are the orexinergic neuronal functions? What conditions can happen if there is something wrong with its function

A

maintain proper vigilance

Wrong: narcolepsy, cataplexy, primary hyprsomnia

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19
Q

What are the GABAergic neuronal functions?

A

go to bed

axons from VLPO project to major nuclei to inhibit primary arousal centers

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20
Q

What are the primary arousal centers?

A

TMN, LH, PPT/LDT, RN, LC

21
Q

What stages are “quiet sleep”? What are the characteristics of this sleep?

A

NREM (N1, N2, N3)

slows down brain activity, heartbeat, respiration, & body temp

22
Q

What stages are “slow wave sleep”? What are the characteristics of this sleep?

A

NREM sleep

low brain activity = low frequency EEG waves

23
Q

What important things happen during N3?

A

takes care of fatigue: brain glycogen & ATP are replenished

tissue repair, GH & prolactin secretion

24
Q

What are the characteristics of N1-NREM stage?

A
  • ~5% total sleep
  • altered state of consciousness (drowsiness)
  • decreased HR, respiration, body temp + relaxed muscles
  • EEG: mixed frequency (alpha & theta)

Hypnic jerks & Hypnagogic hallucinations

25
Q

What are the characteristics of N2-NREM stage?

A
  • ~45% sleep
  • light sleep - theta waves
  • consolidates motor learning
  • Bruxism: pathological teeth grinding happens at this stage
26
Q

What are the EEG characteristics of N2 sleep?

A
  • sleep spindles
    • bursts of high frequency waves - sleep through loud noises
  • K-complexes
    • high amplitude single wave - suppress cortical arousal & keep you asleep
27
Q

What are the characteristics of N3-NREM stage?

A
  • ~25% total sleep
  • glycogen replenishment & tissue repair
  • GH secretion
  • _glymphatic clearanc_e - unique waste clearance system in brain
  • Deep/restful sleep
    • muscles relax & vital signs decrease
    • hard to wake up → groggy, impaired mental status (sleep inertia)
28
Q

What are the EEG characteristics of N3 sleep?

A
  • delta waves (slow wave sleep)
29
Q

What stage of sleep is crucial for declarative memory (ie. facts)?

A

N3

30
Q

Patients with depression get very little of what stage of sleep?

A

N3

31
Q

What stages do sleep-walking, bed-wetting & night terrors occur?

A

N3

32
Q

Snoring occurs in which stage?

A

can occur in all stages, but most frequently N3

33
Q

What are the characteristics of REM stage?

A
  • ~25% total sleep
  • Rapid Eye Movements (EOG)
  • muscle atonia (EMG)
  • dreams (EEG)
  • increase in brain activity & O2 use
  • irregular heart & breathing rates
  • parasympathetic nervous system activation
    • constriction of pupil, erection
34
Q

What phase of sleep is crucial for procedural memory?

A

REM

35
Q

What are the EEG characteristics of REM sleep?

A

beta waves with dominant “PGO activity” = bursts of “sawtooth” wave

  • P : ponto
  • G : genicular
  • O : occipital
36
Q

Why is REM sleep also called paradoxical sleep?

A

increase in brain activity & increase in oxygen use

long, vivid dreams → similar to wakefulness

“shallow stage of sleep”

37
Q

Why do heart attacks often occur in early morning?

A

the fluctuations seen in heart rate & breathing rate during REM sleep

38
Q

What is happening when some people “act out their dreams”?

A
  • REM sleep w/o atonia
  • d/t loss of REM atonic neurons in pons
39
Q

Nightmares occur during what time of sleep? What are the characteristics of nightmares?

A

REM during the later part of the night

can occur in any age, associated with mild physiological changes & you remember the event

40
Q

What is Process H?

A

promotion of sleep

accumulation fo “sleep factors” ie. adenosine

41
Q

What is Process C?

A

circadian rhythm

absence of light decreases alertness - SCN + pineal gland

42
Q

What cardiovascular changes do you see during sleep?

A
  • decrease
    • BP
    • HR
    • CO
    • vasomotor tone
    • plasma volume
43
Q

What respiratory changes do you see during sleep?

A
  • decrease
    • force
    • rate
    • CO2 sensitivity
    • pulmonary ventilation
44
Q

What muscular changes do you see during sleep?

A
  • decrease
    • muscle tone
  • increase
    • repair
45
Q

What urinary changes do you see during sleep?

A
  • decrease
    • urine formation
  • increase
    • phosphate content
    • specific gravity
46
Q

What digestive changes do you see during sleep?

A

relaxed esophageal sphincter

47
Q

What nervous system changes do you see during sleep?

A
  • decrease
    • reflexes
    • sensation
48
Q

What secretion changes do you see during sleep?

A
  • decrease
    • salivary & lacrimal
    • ghrelin
    • BMR
  • increase
    • sweat & gastric
    • leptin

Neuro II (30 decks)

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