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B&B Week 5 Flashcards > Lecture 12: Sleep Medicine Part I > Flashcards

Lecture 12: Sleep Medicine Part I Flashcards

1
Q

What is the suprachiasmatic nucleus?

A

The master clock of the brain
Present in the hypothalamus
Controls circadian rhythms
Each SCN is an individual oscillator based on a fundamental negative feedback loop
-factors stimulate transcription of genes encoding proteins
-As the proteins accumulate, they act as transcriptional repressors of their genes
-this takes one 24 hour cycle
SCN does this even in absence of light-dark cycle

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2
Q

What is the significance of the circadian system?

A

Earth’s orbital mechanics are instantiated in (and entrain) a circadian genetic “clock” and sleep need in the human brain
-unrelenting
Circadian clocks are based on negative feedback loops of SCN
Circadian system interacts with homeostatic system that regulates sleep need

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3
Q

What is wrong with our society today?

A

Society has led to self-imposed conflict between our desire to be awake 24/7 and biological imperative of sleep

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4
Q

What is the significance of the fact that the SCN (circadian clock) is a wake-promoting system?

A

It means that at certain times of the day, it sends out more wake signals than others…
-the homeostatic drive for sleep coupled with low awake signals from SCN leads to sleep

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5
Q

What is the significance of the nonlinear profiles produced by the interaction between need for sleep and circadian drives?

A

Since performance is predicated on wakefulness, the nonlinearity of the relationship makes it difficult to make simple work-hour rules relative to performance and safety during
-working for 16 hours and going to the beach for 16 hours is the same shit in your brain…all awake process

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6
Q

What is the significance of melanopsin cells?

A

Photoreceptors in retinal ganglion cell layers that transmit information about the environmental timing of Earth’s light to SCN
Blue light = awake
-light intensity and durating/timing also plays a role

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7
Q

What hormones do SCN control?

A

Melatonin
More melatonin = go to sleep
Cortisol
More cortisol = wake up

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8
Q

What is the purpose of melatonin?

A

More melatonin = go to sleep

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9
Q

What is the purpose of Cortisol?

A

More cortisol = wake the fuck up

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10
Q

Where can circadian clocks be found in our body?

A

Circadian clocks can be found in ALL tissues throughout all major organ systems
SCN is the master clock that entrains all other peripheral physiologic oscillators

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11
Q

What does the ability to fall asleep and remain asleep depend on?

A

Whether or not you are in right circadian phase

If you are in the WRONG circadian phase while sleeping, then you have disturbed sleep

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12
Q

What is harder? Working 30 hours straight or doing 4 straight night shifts?

A

Working 30 hours than 4 to 5 days of night work
Because we don’t adjust to night work
Night shifts = carcinogenic

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13
Q

How prevalent is sleep in animal kingdom?

A

It is everywhere

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14
Q

What is polysomnography?

A

Surface electrophysiological recordings of

i. brain waves (EEG)
ii. eye movements (EOG)
iii. muscle activity
iv. heart rate
v. respiration
vi. behavior
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15
Q

What are the three aspects of sleep “recovery”?

A
  1. Adequate sleep CONTINUITY
  2. Adequate sleep DEPTH or intensity as seen in slow wave activity (SWA)
  3. Adequate sleep DURATION
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16
Q

What is the characteristic of REM sleep?

A

EEG waves look like waking EEG

  • no thermoregulation
  • REM dreams = bizarre, movement based
  • paralyzed
  • used for procedural memory
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17
Q

What is stage 3 and 4 sleep?

A

The stages right before REM when you have Slow Wave Sleep

-you won’t remember your dream

18
Q

What is the average non-REM to REM cycle?

A

90 minutes

As you sleep longer, the more and more proportion of your sleep is going to be REM

19
Q

How do Orcas and sea lions sleep?

A

Uni-hemispheric sleep

-an adaptation in propoise and many other aquatic mammals so that they can sleep while they swim

20
Q

What is the sleep switch?

A

The ventrolateral preoptic nucleus (VLPO) in hypothalamus

-this is inhibited by GABA as sent by the SCN

21
Q

What happens during the awake brain?

A

The wake drive is regulated by SCN that inhibits the VLPO activity
Allows the sleep centers to be activated and for monoamines to be passed from center to center

22
Q

What happens during the sleeping brain?

A

VLPO send GABA signals to midbrain arousal centers including Raphe, LC, tuberomammilary nucleus (TMN), basal forebrain (BF), perifornical neurons (PeF)

23
Q

What is the ventrolateral preoptic nucleus?

A

The putative sleep switch

Located in the hypothalamus

24
Q

As we age, what happens to our sleep?

A

Periods of sleep during the day become more frequent and sleep during the night is a lot less

25
Q

What neurobehavioral changes occur with loss of sleep?

A
  • mentally slow and inaccurate
  • variable attention and poor focus
  • unreliable memory
  • weak executive decision making
  • emotionally unpredictable
26
Q

Can the effects of sleep loss accumulate over time?

A

Yes

Neurobehavioral deficits can accumulate…overall slowing of brain

27
Q

What do PET scan of sleep-derived adult showing areas of decreased brain metabolism?

A
  1. prefrontal cortex
  2. thalamus
  3. inferior parietal cortex
  4. occipital cortex
28
Q

How powerful is sleep?

A

Sleep can overwhelm goal directed behavior

-example is when people fall asleep at the wheel

29
Q

What are the areas of the brain that are affected by lack of sleep and thereby cause the lapses shown on tests?

A
  1. reduced frontal/parietal control regions to raise activation
  2. reduced visual sensory cortex activation
  3. reduced thalamic activation
  4. reduced connectivity
30
Q

What are the candidate neurological mechanisms for regulation of waking alertness and neurobehavioral functions?

A 
RAS
Basal forebrain
Orexin-hypocretin cells
VLPO
Thalamo-cortical dialogue
31
Q

What are orexin (hypocretin) cells?

A

Neurotransmitter that regulates arousal, wakefulness and narcolepsy

32
Q

Are people aware of how severely lack of sleep is affecting them?

A

No

33
Q

What is front loading your sleep?

A

You want to have a lot of sleep before going into call

Do NOT go into call already sleep deprived

34
Q

Are there differences among us in response to sleep loss?

A

Yes there are

  1. Vulnerable
    • hard to recover after sleep deprivation
  2. Average
    • recovers well after sleep deprivation
  3. Resistant
    • doesn’t matter how long they stay up, they show little deficits
    • any little bit of sleep allows resistant phenotype to recover
35
Q

What is more important? Hours slept or hours worked?

A

Number of hours you sleep is more important than number of hours worked

36
Q

What are the effects of reduced sleep duration on residents?

A

Interns had OR of 2.3 for motor vehicle accident

-more frequent injuries

37
Q

What is the key message of IOM?

A

There is no substitute for adequate sleep

38
Q

What are the ways to be vigilant about your sleep habits?

A
  1. Predict
    • predict when you are going to have less sleep
  2. Prevent
    • front load sleep
  3. Detection of fatigue
  4. Intervene
39
Q

What is the maximum amount of time residents should go without rest?

A

Residents must not work more than 16 hours in a row without rest
-must have protected period of time of at least 5 hours…5 hour protected nap on call
The longer the protected nap time, the greater the behavioral alertness

40
Q

What is Dinges’ takehome point?

A

Sleep is the single most reliable daily performance enhancer

  • use it wisely and professionally
  • get your sleep when you can and learn to recognize sleep loss as a safety and health risk in your patients

B&B Week 5 Flashcards (13 decks)

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