Which brain waves indicate the early stage of sleep, stage 1?

Which brain waves indicate the early stage of sleep, stage 1?

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

Answer: (B)

Theta waves indicate the transition into sleep. As you drift from wakefulness into the first stage of sleep, brain activity slows from the faster rhythms of relaxed wakefulness toward slower theta frequencies, roughly 4–7 Hz. This stage is light sleep, easy to wake from, and sits before deeper sleep stages. Alpha waves happen when you’re awake and relaxed with eyes closed, delta waves dominate deep sleep (stages 3–4), and sleep spindles are brief bursts typical of stage 2. So the presence of theta waves best signals the early, stage-1 sleep.

Theta waves indicate the transition into sleep. As you drift from wakefulness into the first stage of sleep, brain activity slows from the faster rhythms of relaxed wakefulness toward slower theta frequencies, roughly 4–7 Hz. This stage is light sleep, easy to wake from, and sits before deeper sleep stages. Alpha waves happen when you’re awake and relaxed with eyes closed, delta waves dominate deep sleep (stages 3–4), and sleep spindles are brief bursts typical of stage 2. So the presence of theta waves best signals the early, stage-1 sleep.