K-complexes are typically observed during which sleep stages?

K-complexes are typically observed during which sleep stages?

• A. Stage REM
• B. Stage N1
• C. N2/N3
• D. Wakefulness

Answer: (C)

K-complexes are large, brief, biphasic waves that occur during non-REM sleep, most characteristically in stage N2. They often appear spontaneously or in response to a sensorial stimulus, serving as a brief arousal that is quickly dampened so sleep can continue. In stage N2 you also see sleep spindles, and together these features define this stage. While K-complexes can appear during deeper non-REM sleep (stage N3) on occasion, they are not typical of REM sleep (where sawtooth waves predominate) or wakefulness (which shows wakeful alpha and beta activity). Therefore, the best overall match is non-REM sleep stages 2 and 3.

K-complexes are large, brief, biphasic waves that occur during non-REM sleep, most characteristically in stage N2. They often appear spontaneously or in response to a sensorial stimulus, serving as a brief arousal that is quickly dampened so sleep can continue. In stage N2 you also see sleep spindles, and together these features define this stage. While K-complexes can appear during deeper non-REM sleep (stage N3) on occasion, they are not typical of REM sleep (where sawtooth waves predominate) or wakefulness (which shows wakeful alpha and beta activity). Therefore, the best overall match is non-REM sleep stages 2 and 3.