physiology of sleep

Question 1

Functions of REM, and NREM sleep

Answer 1

NREM: brain and body regeneration. REM: brain development and memory

Question 2

Characteristics of REM and NREM sleep

Answer 2

NREM (N1, N2, N3 [SWS] sleep) = high amplitude slow brain waves, increased arousal threshold compared to wake, decreased muscle activity, slow rolling eye-movements, decreased heart rate, respirations and metabolism. REM: every 90 minutes in adults, EEG looks awake but arousal threshold is higher. Active brain in paralyzed body. Temp regulation suspended, brain temp rises, heart and respirations irregular

Question 3

Disorders of arousal

Answer 3

•walking, terrors, confusional arousal, night eating syndrome- usually arise early out of N3, SWS.

Question 4

basal forebrain function in sleep

Answer 4

Adenosine accumulates during wake, reduced during sleep, blocked by caffeine

Question 5

Hypothalamus function in sleep

Answer 5

sleep wake switch

Question 6

thalamus function in sleeps

Answer 6

gate to cortex, spindles, slow wave sleep

Question 7

brainstem function in sleep

Answer 7

ascending cortical activation, REM/SWS switch. Activation of brain stem cholinergic neurons elicits wakefulness

Question 8

Suprachiasmatic nucleus function in sleep

Answer 8

Conveys info from retina to sleep/wake switch in hypothalamus. Circadian clock modulates alertness, Core body temperature (CBT), cortisol and Melatonin secretion

Question 9

Which area of brain is responsible for inhibiting the arousal systems during NREM and REM sleep

Answer 9

neurons of ventrolateral preoptic area

Question 10

Neurotransmitters involved in REM sleep

Answer 10

REM sleep is driven by cholinergic pedunculo-pontine and laterodorsal tegmental (PPT/LDT) neurons. During wake and NREM sleep, these are inhibited by NE, 5HT, HA but during REM the aminergic neurons fall silent, thus disinhibiting the LDT/PPT REM-generating neurons. Also, dopaminergic neurons from ventral tegmental area and substantia nigra ar active

Question 11

What neurotransmitters are involved in atonia of REM sleep

Answer 11

Cholingergic neurons - by activating the medial medulla, which inhibits motor neurons with glycine.

Question 12

Neurotransmitters involved in NREM sleep

Answer 12

GABAergic neurons in ventral lateral pre-optic anterior hypothalamus

Question 13

neurotransmitters involved in wake

Answer 13

Laterodorsal tegmental/ pedunculo-pontine cholinergic neurons, dorsal raphe serotoniergic neurons, locus coeruleus NE neurons, tubomammilary-posterior hypothalamus histaminergic neurons, adenosine in basal forebrain and hypocretin neurons in lateral hypothalamus

Question 14

How do anti histamines cause sleepiness

Answer 14

lipophilic H1 blockers

Question 15

Loss of what kind of cells is seen in narcolepsy with cataplexy

Answer 15

HCT secreting cells

Question 16

function of hypocretin secreting neurons in lateral hypothalamus

Answer 16

arousal, wakefulness, appetite

Question 17

Be able to describe the interaction of the circadian (process C) and homeostatic system (process S) and their effect on wake and on sleep.

Answer 17

Homeostatic drive S: The longer we are awake, the sleepier we get. Mediated by adenosine. Circadian system C: Sleepiness waxes and wanes under influence of circadian alerting system in the suprachiasmatic nuclei, and is linked to core body temperature.

Question 18

Discuss the pathway of the circadian system

Answer 18

Light travels to suprachiasmatic nucleus (SCN) via the retinohypothalamic tract (RHT) > The SCN signals the pineal gland via the superior cervical ganglion & inhibits the production of melatonin. Melatonin normally reduces SCN activity and arousal, so in light SCN activity is increased and arousal occurs.

Question 19

In absence of light, what happens

Answer 19

People “free run” and operate on a 24.2 hour day

Question 20

Tool to measure sleepiness

Answer 20

Epworth sleepiness scale - asks how likely you are to fall asleep in certain situations to sort out sleepy from fatigued. 1-6: getting enough sleep. 7-8: average sleep deprived american. 9+: very sleepy and need follow up

Question 21

Causes of high epworth rating

Answer 21

insufficient sleep, circadian rhythm disorder (shift work, jt lag), sleep apnea, narcolepsy, head injury, depression, drug use or withdrawal, medical illness

Question 22

Causes of sleepiness with low epworth rating

Answer 22

fatigue: anxiety and depression, conditioned/learned insomnia

Question 23

behavioral causes of insomnia or excessive daytime sleepiness

Answer 23

bedroom not dark or quiet, irregular sleep and wake times, big meals before bed, co-sleeping with pets, alcohol, caffeine, loud bed partner

Question 24

Circadian alerting system is linked to what?

Answer 24

core body temp: People sleep best on the descending curve of their CBT and spontaneously awake about 2-3 hours after lowest CBT and CBT begins to rise.
core body temp: People sleep best on the descending curve of their CBT and spontaneously awake about 2-3 hours after lowest CBT and CBT begins to rise.

Question 25

Delayed sleep phase syndrome

Answer 25

aka night owls- “insomnia” when trying to sleep at socially appropriate time or EDS when awakened for school or work before enough sleep & before alerting rhythms rise.

Question 26

Advanced sleep phase syndrome

Answer 26

aka “larks”- “want” to sleep and wake early. If remain awake to watch news, they still wake early and  EDS; their early morning awakening misinterpreted as insomnia due to depression.

Question 27

Obstructive sleep apnea

Answer 27

increased work of breathing from snoring, to upper airway resistance syndrome, to respiratory effort related arousals, to hypopneas to apneas

Question 28

Obstructive sleep apnea comorbid conditions

Answer 28

Increased stress leads to a pro-inflammatory response increasing risk of CVHD, stroke, HTN and pulmonary hypertension and can predict the development of depression. In kids may be one cause of attentional difficulties since tired kids get hyperactive and have decreased ability to concentrate and lead to wrong dx of ADHD

Question 29

Categories of insomnia

Answer 29

1. learned: hyper-arousal and learned, and not caused by other condition. 2. Co-morbid: due ot mediical, psychiatric, pain, restless legs, circadian problems, narcolepsy, meds

Question 30

Insomnia treatment

Answer 30

sleep restriction and stimulus control

Question 31

restless leg syndrome

Answer 31

•waking discomfort. Urge to move legs and/or arms, with onset or worsened by rest, usually at night, and somewhat relieved by movement. ? Associated with HTN

Question 32

Restless leg syndrome treatment

Answer 32

iron replacement if serum ferritin is <55

Question 33

What stage of sleep does sleep walking/night terrors occur

Answer 33

in first part of sleep period.

Question 34

What is REM sleep behavior disorder

Answer 34

loss of muscle paralysis and acting out dreams in later part of nght when REM is more prevalent. Common in men <50

Question 35

cause of narcolepsy

Answer 35

lesions in hypocretin system- loss of boundaries between sleep and wakefullness. Patients quickly enter REM sleep at any time, have loss of muscle tone while awake (cataplexy), sleep paralysis, and hypnagogic hallucinations

Question 36

Narcolepsy treatment

Answer 36

naps, stimulants, sodium oxybutyrate