K complexes are often seen

K complexes are often seen

• A. In stage 1 sleep
• B. In stage 2 sleep
• C. In stage 3 sleep
• D. In REM

Answer: (B)

K complexes occur during stage 2 non-REM sleep. They are large, high-amplitude biphasic waves that can appear spontaneously or in response to a sensory stimulus, and they commonly accompany sleep spindles in this stage. This combination marks a lighter phase of non-REM sleep where the brain can still react to stimuli but remains largely asleep, helping protect sleep from being easily disrupted. In other sleep stages, these waves are not typical: stage 1 shows lighter, transitional theta activity without K-complexes; stage 3 is dominated by delta, slow-wave activity; REM sleep features rapid eye movements and a different, low-amplitude, mixed-frequency EEG with sawtooth waves rather than K-complexes. Thus, the sign that best reflects a K complex is stage 2 sleep.

K complexes occur during stage 2 non-REM sleep. They are large, high-amplitude biphasic waves that can appear spontaneously or in response to a sensory stimulus, and they commonly accompany sleep spindles in this stage. This combination marks a lighter phase of non-REM sleep where the brain can still react to stimuli but remains largely asleep, helping protect sleep from being easily disrupted. In other sleep stages, these waves are not typical: stage 1 shows lighter, transitional theta activity without K-complexes; stage 3 is dominated by delta, slow-wave activity; REM sleep features rapid eye movements and a different, low-amplitude, mixed-frequency EEG with sawtooth waves rather than K-complexes. Thus, the sign that best reflects a K complex is stage 2 sleep.