Which stage 2 feature appears as brief bursts of rapid electrical activity?

Which stage 2 feature appears as brief bursts of rapid electrical activity?

• A. Alpha waves
• B. Delta waves
• C. Sleep spindles
• D. Theta waves

Answer: (C)

In stage 2 sleep, the hallmark EEG feature is sleep spindles. These are brief bursts of rapid electrical activity, about 12 to 14 Hz, lasting roughly 0.5 to 1.5 seconds. They arise from thalamocortical interactions and help protect sleep by filtering sensory input as you pass into deeper sleep. Other waveforms light up different parts of the sleep story: alpha waves appear when you're awake and relaxed with eyes closed; delta waves are the slow, large-amplitude patterns seen in deep sleep (stages 3–4); theta waves show up in lighter sleep and during the transition into sleep (N1).

In stage 2 sleep, the hallmark EEG feature is sleep spindles. These are brief bursts of rapid electrical activity, about 12 to 14 Hz, lasting roughly 0.5 to 1.5 seconds. They arise from thalamocortical interactions and help protect sleep by filtering sensory input as you pass into deeper sleep.

Other waveforms light up different parts of the sleep story: alpha waves appear when you're awake and relaxed with eyes closed; delta waves are the slow, large-amplitude patterns seen in deep sleep (stages 3–4); theta waves show up in lighter sleep and during the transition into sleep (N1).