Best Practices & Methodologies Flashcards

Which EEG feature is required to score an epoch as stage N2 sleep?

Answer: At least one K-complex or sleep spindle in the absence of arousal

Stage N2 requires one or more K-complexes or sleep spindles not associated with arousal, in the absence of sufficient slow-wave activity for N3.

Stage N3 is scored when high-amplitude slow-wave activity occupies what proportion of an epoch?

Answer: >20%

N3 (slow-wave sleep) is scored when ≥20% of the epoch contains waves with frequency 0.5–2 Hz and peak-to-peak amplitude >75 µV.

REM sleep is identified by which combination of polysomnographic features?

Answer: Low-amplitude mixed-frequency EEG, low chin EMG tone, and rapid eye movements

REM sleep is characterized by low-amplitude mixed-frequency EEG, atonic (low) chin EMG, and rapid eye movements.

According to AASM rules, an arousal during NREM sleep is scored when there is an abrupt shift in EEG frequency lasting at least how long?

Answer: 3 seconds

A NREM arousal requires an abrupt EEG frequency shift lasting ≥3 seconds, preceded by at least 10 seconds of stable sleep.

What EEG waveform defines stage N1 sleep in patients who generate a well-defined alpha rhythm while awake?

Answer: Replacement of alpha rhythm by low-amplitude mixed-frequency activity

In patients with alpha rhythm, N1 is scored when alpha is attenuated and replaced by low-amplitude mixed-frequency (predominantly 4–7 Hz) EEG activity.

Sawtooth waves are a characteristic EEG feature associated with which sleep stage?

Answer: Stage R (REM)

Sawtooth waves—serrated, sharply contoured 2–6 Hz waves—are a characteristic EEG feature of REM sleep, often preceding bursts of rapid eye movements.

When scoring an epoch that contains both stage N2 features and stage N3 slow-wave activity, which rule applies?

Answer: Score N3 if slow-wave activity comprises ≥20% of the epoch

AASM rules score an epoch as N3 when ≥20% of the epoch contains qualifying slow-wave activity, regardless of co-occurring N2 features.