Sleep

Question 1

What methods are used to define sleep stages?

Answer 1

EEG
EOG (electro-oculogram)
EMG of chin muscle tone

additional methods: respiratory effort, oxygenation, ECG, surface EMG

Question 2

What are some key neurotransmitters of waking state?

Answer 2

Histamine (tubomamillary nucleus)
NE (locus ceruleus)
serotonin (raphe nuclei)
acetylcholine (basal forebrain)

Question 3

What are the EEG, EOG, and muscle tone features of waking state?

Answer 3

EEG: Low voltage, high frequency, alpha waves (8-13 hz)
EOG: rapid, blinking
Muscle tone: high

Question 4

What are the EEG, EOG, and muscle tone features of N1 state?

Answer 4

EEG: <50% alpha waves
replaced by theta, (4-7 Hz)
vertex waves
EOG: slow roving eye movements
Muscle tone: high

Question 5

What are the EEG, EOG, and muscle tone features of N2 state?

Answer 5

EEG: vertex K: high voltage positive and negative discharges with spindles (11-16 Hz)
Spindles ~5 seconds
EOG: still
Muscle tone: high

Question 6

What are the EEG, EOG, and muscle tone features of N3/slow wave/ Delta sleep?

Answer 6

EEG: slow wave, high voltage (>75 uV), low frequency (<2Hz)
EOG: still
Muscle tone: low
Reduced BP, HR, cardiac output, RR
GH release

Question 7

What are the EEG, EOG, and muscle tone features of REM sleep?

Answer 7

EEG: mixed frequency, low voltage, sawtooth waves
EOG: RIM
Muscle tone: very low
Cholinergic brain state
irregular respiration
Arrhythmias, heart rate variation
dreaming

Question 8

What is the difference between tonic and phasic REM sleep?

Answer 8

Tonic: impaired thermoregulation, hypotension, bradycardia, increased cerebral blood flow, increased ICP, increased RR, erection, atonia
phasic: vasoconstriction, increased BP, tachycardia, further increase in cerebral blood flow and RR

Question 9

What part of the midbrain is involved in REM sleep?

Answer 9

Pons: REM on/off cells

Question 10

How long is the sleep cycle?

Answer 10

90 minutes

Question 11

how do the characteristics of the 4 stages change through a full night’s sleep?

Answer 11

increasing REM time and decreasing N3
1 5%
2 50%
3 20%
REM 25%

Question 12

A lesion in what location causes narcolepsy?

Answer 12

posterior hypothalamus

Question 13

What nucleus’s activity is correlated with sleep ONSET?

Answer 13

VLPO (anterior hypothalamus)

Question 14

Does dimlight suppress melatonin?

Answer 14

Yes. Melatonin increases in the evening

Question 15

How many hours do new borns sleep? what percentage is REM?

Answer 15

18 hours, 50%

Question 16

What changes occur to delta sleep with age?

Answer 16

decrease, although this could be an artifact of definitional problem (EEG slows down with age, and leads to the appearance of reduced delta sleep)

Question 17

What’s the effect of antihistamines on sleepiness?

Answer 17

increase sleepiness

Question 18

What’s the effect of benzodiazepines on sleep?

Answer 18

Reduced delta sleep

Question 19

What’s the effect of TCA/SSRI/MAO-I on sleep?

Answer 19

increase RIM latency, reduce REM

Question 20

What are the key markers of circadian rhythm?

Answer 20

cortisol, temperature, REM timing

Question 21

When is cortisol/GH produced?

Answer 21

Cortisol in the morning, with or without sleep

GH only following sleep (N3)

Question 22

Where is the centre of control for circadian rhythms?

Answer 22

Suprachiasmatic nucleus (SCN)

Question 23

What are the afferents for SCN?

Answer 23

retinohypothalamic, lateral geniculate nucleus, raphe nuclei

Question 24

What are the efferents for SCN?

Answer 24

paraventricular nuclei, hypothalamus, thalamus, dorsomedial hypothalamus