RPSGT Core Concepts & Fundamentals 5 — Questions and Answers
Question 1: In a healthy young adult, approximately what percentage of total sleep time is spent in REM sleep?
- 5–10%
- 15–20%
- 20–25% (Correct answer)
- 35–40%
Correct answer: 20–25%
REM sleep constitutes approximately 20–25% of total sleep time in healthy young adults.
Question 2: What artifact in PSG is most commonly caused by 60 Hz electrical interference from nearby equipment?
- Sweat artifact
- Electrode pop artifact
- 60 Hz (AC) artifact (Correct answer)
- Movement artifact
Correct 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.
Question 3: The process by which the circadian clock is reset by external cues such as light is called:
- Entrainment (Correct answer)
- Homeostasis
- Actigraphy
- Phase delay
Correct answer: Entrainment
Entrainment is the synchronization of the internal biological clock to external zeitgebers (time cues) such as light.
Question 4: Which of the following EEG waveforms is characterized by a frequency of 0.5–2 Hz and amplitude greater than 75 µV?
- Alpha waves
- Sleep spindles
- K-complexes
- Delta waves (Correct answer)
Correct 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.
Question 5: What is the function of the chin (submental) EMG channel in a standard PSG recording?
- Measure respiratory effort
- Assess limb movement during sleep
- Evaluate muscle tone to help identify REM sleep (Correct answer)
- Detect bruxism only
Correct 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.
Question 6: Stage N1 sleep is best characterized by which EEG finding?
- Predominant alpha activity
- Low-voltage mixed-frequency activity with vertex sharp waves (Correct answer)
- Frequent K-complexes and spindles
- High-amplitude delta waves
Correct 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.
Question 7: Which of the following best describes the 'two-process model' of sleep regulation?
- Sleep is governed by REM pressure and NREM pressure alternating cyclically
- Sleep is regulated by the interaction of circadian rhythms (Process C) and homeostatic sleep drive (Process S) (Correct answer)
- Sleep quality depends on two factors: sleep duration and sleep onset latency
- Two brain regions — the SCN and the pineal gland — independently control sleep timing
Correct 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).
RPSGT Core Concepts & Fundamentals 5
In a healthy young adult, approximately what percentage of total sleep time is spent in REM sleep?