Which stage 2 sleep feature is a large, slow wave event?

Which stage 2 sleep feature is a large, slow wave event?

• A. Sleep spindles
• B. Alpha waves
• C. Theta waves
• D. K complexes

Answer: (D)

In stage 2 sleep the EEG shows two key features: sleep spindles and K-complexes. The large, slow wave described is the K-complex. It appears as a sharp, high-amplitude negative deflection followed by a slower positive wave, typically lasting a fraction of a second to a couple of seconds. K-complexes often occur in response to stimuli but don’t necessarily wake you, helping to protect sleep while still letting the brain process sensory input. Sleep spindles, by contrast, are brief bursts of higher-frequency activity (roughly 12–16 Hz); alpha waves are the 8–12 Hz pattern seen with relaxed wakefulness, and theta waves (about 4–7 Hz) appear in lighter sleep. So the large slow wave in stage 2 is the K-complex.

In stage 2 sleep the EEG shows two key features: sleep spindles and K-complexes. The large, slow wave described is the K-complex. It appears as a sharp, high-amplitude negative deflection followed by a slower positive wave, typically lasting a fraction of a second to a couple of seconds. K-complexes often occur in response to stimuli but don’t necessarily wake you, helping to protect sleep while still letting the brain process sensory input. Sleep spindles, by contrast, are brief bursts of higher-frequency activity (roughly 12–16 Hz); alpha waves are the 8–12 Hz pattern seen with relaxed wakefulness, and theta waves (about 4–7 Hz) appear in lighter sleep. So the large slow wave in stage 2 is the K-complex.