EEG Sleep Staging and Sleep EEG 5

Question 1

Sleep efficiency is calculated as:

Accepted Answer

Total sleep time divided by time in bed × 100

Answer

Sleep efficiency = (TST / TIB) × 100; a value ≥85% is generally considered normal in adults.

Question 2

Which sleep stage is most suppressed by benzodiazepine hypnotics?

Accepted Answer

N3 slow-wave sleep

Answer

Benzodiazepines markedly reduce N3 (slow-wave sleep) amplitude and duration while increasing spindle activity in N2.

Question 3

A 35-year-old has a sleep onset latency to REM (SOREMP) of 8 minutes on overnight PSG. This finding is most suggestive of:

Accepted Answer

Narcolepsy

Answer

A REM latency of ≤20 minutes (SOREMP) on nocturnal PSG is a key diagnostic criterion for narcolepsy.

Question 4

In healthy young adults, what percentage of total sleep time is typically spent in REM sleep?

Accepted Answer

20–25%

Answer

REM sleep constitutes approximately 20–25% of TST in healthy young adults, decreasing with advancing age.

Question 5

The phenomenon of 'REM rebound' after REM-suppressing medication withdrawal is best explained by:

Accepted Answer

Homeostatic pressure accumulating during REM deprivation

Answer

When REM-suppressing drugs are withdrawn, accumulated homeostatic REM pressure results in increased REM percentage and shortened REM latency.

EEG - Electroencephalography Practice Test