Core Concepts & Fundamentals Flashcards

In a healthy young adult, approximately what percentage of total sleep time is spent in REM sleep?

Answer: 20–25%

REM sleep constitutes approximately 20–25% of total sleep time in healthy young adults.

What artifact in PSG is most commonly caused by 60 Hz electrical interference from nearby equipment?

Answer: 60 Hz (AC) artifact

60 Hz AC artifact appears as a regular, high-frequency hum on the tracing caused by alternating current electrical interference.

The process by which the circadian clock is reset by external cues such as light is called:

Answer: Entrainment

Entrainment is the synchronization of the internal biological clock to external zeitgebers (time cues) such as light.

Which of the following EEG waveforms is characterized by a frequency of 0.5–2 Hz and amplitude greater than 75 µV?

Answer: Delta waves

Delta waves are defined by frequencies of 0.5–2 Hz and amplitudes exceeding 75 µV, and they define slow-wave sleep.

What is the function of the chin (submental) EMG channel in a standard PSG recording?

Answer: Evaluate muscle tone to help identify REM sleep

Submental EMG monitors chin muscle tone; reduced or absent tone during REM helps confirm REM sleep staging.

Stage N1 sleep is best characterized by which EEG finding?

Answer: Low-voltage mixed-frequency activity with vertex sharp waves

N1 is defined by low-voltage mixed-frequency EEG (2–7 Hz), often with vertex sharp waves and reduction of alpha activity.

Which of the following best describes the 'two-process model' of sleep regulation?

Answer: Sleep is regulated by the interaction of circadian rhythms (Process C) and homeostatic sleep drive (Process S)

The two-process model (Borbély) describes sleep as regulated by the circadian clock (Process C) and homeostatic sleep pressure that builds during wakefulness (Process S).