Sleep

Question 1

Define normal sleep.

Answer 1

Reversible behavioral state characterized by disengagement from the environment and restoration of body and mind

Question 2

What are the two kinds of sleep, when do they predominate in a given cycle, and what are they linked to?

Answer 2

Non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep; NREM predominates in the first half of the night (and is linked to amount of time we were previously awake), while REM is more common in the latter half (and is linked to circadian rhythm)

Question 3

How does sleep change over time, including the proportion of REM and NREM? How does the wake/ sleep pattern change?

Answer 3

Total quantity of sleep decreases over time, while proportion of REM to NREM goes from 50/50 as an infant, to 80/20 as adults; as we get older, sleep gradually becomes restricted to the night (newborns, on the other hand, sleep on a regular pattern throughout a 24 hr period)

Question 4

Which branch of the autonomic nervous system predominates during sleep, and what effect does this have on body functions?

Answer 4

The parasympathetic system predominates, leading to reduced heart rate, blood pressure, ventilation, and a lower body temperature

Question 5

Sleep is regulated by the interaction between which two processes? Briefly describe each process

Answer 5

Homeostatic Sleep Drive (i.e., Process S) (which builds pressure for sleep with increasing wakefulness), and Circadian Rhythm (i.e., Process C) (which intrinsically aligns sleep with the 24 hr day; generated in SCN of hypothalamus)

Question 6

What are Zeitgebers, and what role do they play in circadian rhythms?

Answer 6

Zeitgebers are environmental cues (like light, meals, and activity) that entrain circadian rhythms to external time.

Question 7

What is “sleep debt,” and why can’t people adapt to chronic sleep deprivation?

Answer 7

Sleep debt is the cumulative effect of insufficient sleep, and people cannot adapt (i.e., get used to sleeping less) because recovery requires extended rest

Question 8

What types of tasks are most impaired by sleep loss? What tasks are not impacted by sleep loss if the individual is highly motivated?

Answer 8

Those which require sustained attention, are memory based, and/ or are monotonous

Short, simple tasks

Question 9

What safety risks are associated with sleep deprivation in healthcare workers and drivers?

Answer 9

Increased risk of medical errors, needlestick injuries, near-crashes while driving, and impaired alertness (especially after night shifts)

Question 10

What physiologic parameters are recorded during polysomnography (i.e., the “gold standard” for obstructive sleep apnea diagnosis)?

Answer 10

EEG, ECG, eye movements (EOG), muscle activity (EMG), leg movements, airflow, respiratory effort, and oxygen saturation.

Question 11

How does home sleep apnea testing differ from in-lab polysomnography?

Answer 11

It records fewer parameters (airflow, respiratory effort, oxygen) and is limited to evaluating sleep apnea, often underestimating its severity.

Question 12

What findings on the Multiple Sleep Latency Test (MSLT) are characteristic of narcolepsy?

Answer 12

Mean sleep latency under 8 minutes and two or more REM periods across five naps.

Question 13

What are the diagnostic features of insomnia, and what treatments are most effective?

Answer 13

Insomnia lasts at least one month with hyperarousal and difficulty initiating/maintaining sleep.

Cognitive-behavioral therapy (stimulus control, sleep restriction) is most effective; medications may be used.

Question 14

What are hallmark symptoms of obstructive sleep apnea (OSA)? What medical conditions is it associated with?

Answer 14

Loud snoring, witnessed apneas, daytime sleepiness, and morning headaches

Associated with hypertension, GERD, and cardiovascular disease.

Question 15

What classic tetrad of symptoms is associated with narcolepsy?

Answer 15

Excessive daytime sleepiness, cataplexy (i.e., sudden loss of muscle tone), hypnagogic hallucinations, and sleep paralysis.

Question 16

Give an example of an NREM parasomnia and a REM parasomnia.

Answer 16

NREM: sleepwalking or sleep terrors.

REM: REM sleep behavior disorder (acting out dreams – e.g., singing, walking/ running, violent behaviors)