RPSGT Sleep Staging & Scoring Flashcards

What distinguishes Stage N1 from Stage Wake in a subject who generates occipital alpha rhythm?

Answer: Alpha activity present for <50% of the epoch

N1 is scored when alpha activity occupies <50% of the epoch, replaced by low-amplitude mixed-frequency activity.

Sawtooth waves during polysomnography are most commonly associated with which sleep stage?

Answer: REM

Sawtooth waves (2–6 Hz, notched waveforms) are a characteristic feature of REM sleep, often preceding bursts of rapid eye movements.

An EEG frequency shift qualifies as an arousal in AASM scoring if it lasts a minimum of how many seconds?

Answer: 3 seconds

AASM defines an arousal as an abrupt EEG frequency shift lasting ≥3 seconds, preceded by ≥10 seconds of stable sleep.

Which of the following correctly states the amplitude criterion for slow wave activity in N3 scoring?

Answer: Peak-to-peak >75 µV in frontal leads

AASM requires slow waves to have peak-to-peak amplitude >75 µV measured over the frontal derivations.

What frequency range defines the theta activity that predominates in Stage N1 sleep?

Answer: 4–7 Hz

Theta activity (4–7 Hz) is the predominant EEG frequency in Stage N1, replacing the alpha rhythm seen during wakefulness.

In subjects who do not generate occipital alpha activity, which criterion is used to distinguish Stage Wake from Stage N1?

Answer: Presence of irregular conjugate eye movements and/or eye blinks

In non-alpha generators, Stage W is scored by the presence of eye blinks, reading eye movements, or irregular conjugate eye movements with normal or high-amplitude mixed-frequency EEG.

How is a sleep cycle most accurately defined in standard PSG scoring?

Answer: One NREM period followed by one REM period

A sleep cycle consists of one NREM period (N1–N2–N3) followed by a REM period, typically repeating every 90–110 minutes.