Sleep Staging and Sleep EEG Flashcards

Sleep efficiency is calculated as:

Answer: Total sleep time divided by time in bed × 100

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

Which sleep stage is most suppressed by benzodiazepine hypnotics?

Answer: N3 slow-wave sleep

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

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

Answer: Narcolepsy

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

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

Answer: 20–25%

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

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

Answer: Homeostatic pressure accumulating during REM deprivation

When REM-suppressing drugs are withdrawn, accumulated homeostatic REM pressure results in increased REM percentage and shortened REM latency.

Which of the following is the correct AASM criterion for scoring N3 sleep?

Answer: ≥20% of the epoch consists of waves 0.5–2 Hz with amplitude >75 µV

AASM rules require that ≥20% of the 30-second epoch contain slow waves (0.5–2 Hz, peak-to-peak >75 µV) to score N3.

During an MSLT nap, a patient falls asleep in 4 minutes and enters REM sleep. How many such SOREMPs across 5 naps are needed to support a narcolepsy diagnosis?

Answer: ≥2 SOREMPs

ICSD-3 criteria require a mean sleep latency ≤8 minutes AND ≥2 SOREMPs across 5 MSLT nap opportunities to diagnose narcolepsy.