Sleep Disorders

Question 1

Stages of sleep?

Answer 1

Subject progress down through stages 1, 2, 3, and 4 of non-rapid eye movement (NREM) sleep, then reverses “up” stages 3 or 2 before the first rapid eye movement (REM) stage

Stage 1 - drowsiness and early EEG slowing
Stage 2 - asleep but easily aroused, unique sleep spindles on EEG
Stage 3 and 4 - harder to arouse, delta wave (slowest EEG activity)

Question 2

Frequency of REM?

Answer 2

90 minutes after sleep begins, reoccurs about every 90 minutes, lasts only a few minutes at first, then lengths in duration to an hour or so

Question 3

More time is spent in ___ stages earlier in sleep, while ___ occurs later in sleep.

Answer 3

Stages 3 and 4; REM

Question 4

What happens during REM?

Answer 4

Maximal limb hypotonia - subtle twitches of the face and limbs, irregular pulse and breathing, usually horizontal, rapid, conjugate eye movements

EEG similar to wake state

Recallable dreams

Important for reinforcing memory traces

Question 5

Deprivation or suppression of REM sleep results in what?

Answer 5

Anxiety, hostility, hallucinations, amnesia

Question 6

What drugs can suppress REM?

Answer 6

Barbiturates

Question 7

Subjects who are deprived of sleep overall will have ___ onset of REM.

Answer 7

Earlier

Question 8

Changes in sleep throughout life?

Answer 8

Newborns sleep ~15 hours daily - frequent yet shorter sleep periods

Sleep lasts about 6 hours in the elderly, although they have more frequent drowsy periods

% of REM sleep falls from almost 50% in infants to about 20% in older subjects

% of slow wave sleep (stages 3 and 4) decreases, % of stage 1 and 2 sleep increases with age

Question 9

What system is important for arousal or wakefulness?

Answer 9

Ascending reticular activating system (ARAS)

Question 10

Pathway of the ARAS?

Answer 10

Arises from the rostral pons, caudal midbrain, posterior hypothalamus, and basal forebrain nuclei to activate the cortex directly or via the thalamus

Suppresses the ventrolateral preoptic area of the hypothalamus

Question 11

What does the pontine REM center do?

Answer 11

Activates the brain stem gaze centers responsible for rapid, conjugate eye movement during REM and induces hypotonia and increased autonomic activity by descending reticulospinal pathways

Question 12

REM and NREM sleep are promoted by the ___ of the ventrolateral hypothalamus.

Answer 12

Preoptic

Question 13

What controls the circadian sleep-wake cycle?

Answer 13

Hypothalamic suprachiasmatic nucleus

Question 14

Effects of sleep apnea?

Answer 14

Excessive daytime sleepiness

Nocturnal hypoxemia -> pulmonary HTN or arrhythmias

Question 15

Features and Rx of OSA?

Answer 15

Caused by upper airway obstruction despite contraction of the diaphragm and chest wall muscles

Obese, anatomy predisposing

Dx with sleep study (EEG, EKG, oximetry, respiratory and video monitoring)

Rx with weight loss, surgical correction of the upper airway, mask devices that deliver pressurized oxygen)

Question 16

What is central sleep apnea?

Answer 16

Occurs in the absence of any diaphragmatic or respiratory effort to breathe

Question 17

What is narcolepsy?

Answer 17

Inherited disorder consisting of REM sleep occurring at inappropriate times

Features: narcoleptic attacks, cataplexy (periodic loss of muscle tone for seconds to several minutes in duration, often provoked by emotional triggers), sleep paralysis, visual hallucinations (hypnagogic, hypnopompic)

Question 18

Pathogenesis of narcolepsy?

Answer 18

Deficiency of certain neurons in the dorsoalteral hypothalamus which release the excitatory peptide hypocretin 9aa orexin) and project to the locus ceruleus and cholinergic neurons of the basal forebrain

Question 19

Dx narcolepsy?

Answer 19

Multiple sleep latency tests, where the abnormally early onset of REM is recorded

Question 20

Rx narcoleposy?

Answer 20

Methylphenidate (wakefulness)
Modafanil, armodafinil (helps treat daytime somnolence)
Drugs with REM suppressing properties like TCAs can help reduce cataplexy