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Quiz 4 Neurology > Sleep and wakefulness > Flashcards

Sleep and wakefulness Flashcards

1
Q

Delta waves

A

deepest sleep <4Hz

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2
Q

Alpha and beta waves

A

awake
Alpha=8-13 Hz
Beta=14-30 Hz

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3
Q

Sleep state is characterized by which wave states?

A 
Theta waves (4-7 Hz)
Delta waves (<4Hz)
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4
Q

What are the three brain states?

A

Awake
NREM
REM

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5
Q

What is the alpha rhythm? Where in the brain would you see activity?

A

Eyes are open
Rapid eye movements
Normal muscle tone

See activity in the occipital region. this is the hallmark of wakefulness

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6
Q

What are the different stages of sleep, on the way to REM?

A

N1=light sleep
N2=filler sleep
N3: deep sleep-slow waves
REM sleep

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7
Q

Describe N1 sleep:

A 
LIGHT SLEEP
o	Alpha drops out and replaced by theta activity
o	Vertex sharp waves
o	Central apneas
o	Slower eye movements
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8
Q

Describe N2 sleep:

A

o Continued theta slowing
FILLER SLEEP
o Sleep spindles: 13-14 hz in the beta range that are football shaped
o K complexes: Large amplitude/biphasic evoked by stimulation (noise). Hypothesized to keep us asleep despite stimuli

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9
Q

Describe N3 sleep:

A 
Deep sleep
o	>20% slow wave activity
o	.5-2 Hz slow waves
o	>75uV amplitude slow waves (tall!)
o	Highest arousal threshold of sleep
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10
Q

Describe REM sleep

A

o Stage-1 like EEG
o Sawtooth waves= sharp theta waves
o Rapid eye movements
o Reticular activation – desynchronization
o Phasic and tonic movements
o Muscle atonia
o Cognitive activity mostly in occipital lobes
o PGO spikes
o Autonomic instability—irregularity in respiration, arrhythmias. Switching back and forth between sympathetic and parasympathetic tone

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11
Q

NREM and REM cycle every how many minutes?

A

90 minutes.

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12
Q

When does N3 predominate? When does REM predominate?

A

o N3 predominates in the first 1/3 of night

o REM predominates in the last 1/3 of night

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13
Q

What sleep state predominates overall usually?

A

We are in N2 50% of the time we are sleeping

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14
Q

Describe Non-Rem sleep

A 
Decreased HR and BP
Low O2, high CO2 and slow breathing
Normal thermal regulation
Reduced muscle tone
Reduced CBF
Reduced cognition
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15
Q

Describe REM sleep

A

Variable sympathetic activity (breathing, HR, BP)
Very low O2, high CO2, slow breathing
Minimal muscle tone
Poikilothermic: Variable body temperature
Increased CBF
Bizarre cognition

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16
Q

Describe fetal sleep–how many hours?

What percent is active sleep vs quiet sleep?

A

Feti sleep 16-18 hrs each day

50/50 activity. Adults only spend 25% of their sleep cycle in REM sleep

17
Q

What happens to slow wave sleep as we age?

A

Slow decline in slow wave sleep

18
Q

What are Zeitgebers?

A

External cues which help us regulate circadian rhythms

19
Q

What is entrainment?

A

Adjustment of circadian to surrounding cues. Bright light in evening will cause a phase delay (ie teenagers watching TV at night will go to bed at 3AM and sleep till NOON)

20
Q

What is free running?

A

Persistence of circadian rhythms during constant conditions of light or darkness.Absence of Zeitgebers

21
Q

What nucleus is responsible for regulating circadian rhythms?

A

SCN

22
Q

what happens when you ablate the SCN?

A

Loss of rhthmycity

23
Q

what happens when you isolate the SCN?

A

Loss of zeitgeber response. Cannot incorporate external cues into circadian rhythm

24
Q

What cues cause melatonin to be released? What does melatonin do?

A

Melatonin is induced by darkness. It helps to shift the phase of the cycle towards sleep.

25
Q

What causes me to feel sleepy after a long day in the library?

A

Process S: homeostatic mechanism related to prior sleep and wake states. Adenosine is the main driver. Levels of adenosine build over the day, causing us to feel sleepy.

26
Q

Describe the pathophysiological mechanism by which adenosine works.

A

Adenosine inhibits basal forebrain Ach neurons. Caffeine works by inhibiting adenosine activity.

27
Q

What is process C?

A

Driven by circadian rhythm. Peaks in the evening. Helps us to stay awake at night.

28
Q

What system promotes a wakeful state?

A

The ascending reticular activating system

29
Q

Where does the ARAS project to?

A
  1. Thalamus
  2. Lateral hypothalamus
  3. Basal forebrain
  4. Cortex
30
Q

Which key components of the ARS are active during wake cycles? What neurotransmitter does each use?

A

Lateral Dorsal Tegmentum (LDT)/ pedunculopontine tegmentum (PPT) – Acetylcholine (Ach)
Locus Coeruleus – Norepihepherin (NE)
Raphe – Serotonin (5HT)
Tuberomamillary Nucleus (TMN) – Histamine (His)

31
Q

What is the role of hypocretin/orexin?

A

Works on hypothalamus. Prevent unwanted sleep transitions. Orexin neurons of the lateral hypothalamus are active during wakefulness and stimulate activity in the ARAS

32
Q

Where does dopamine act?

A

Brainstem/hypothalamus

33
Q

What happens with a lack of orexin?

A

Narcolepsy. It’s important in the maintenance of a wakeful state

34
Q

What is the role of the Ventrolateral preoptic area.

A

Releases GABA to inhibit ARAS and orexin. Crucial for sleep onset

In contrast, LC, TMN, RAPHE work with ARAS to keep us awake

35
Q

Describes what happens to generate REM sleep

A

Decreased firing in:
1. Locus coeruleus (NE), TMN (histamine) and raphe (5HT)

Increased firing in:
1. LDT and PPT neurons (Ach) (lateral dorsal tegmentum and pedunculopontine tegmentum)

Generation of PGO spikes
Descending motor inhibition

36
Q

What are the postulated functions of sleep?

A
  1. Restoration: tissue repair, anabolic steroids, rebound slow wave sleep, downregulation of normal physiologic functions
37
Q

What are the fxns of REM sleep?

A
  1. learning/memory
  2. promotion of CNS development
  3. Restoration of neurotransmitters
  4. Maintenance of circuitry formed during the day
  5. Memory fxn

Quiz 4 Neurology (5 decks)

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