Which EEG pattern is associated with drowsiness?

The EEG pattern associated with drowsiness is alpha waves. Alpha waves typically occur at a frequency of 8 to 12 Hz and are most prominent when a person is awake but relaxed, often with their eyes closed. This brain wave activity signifies a state of calm alertness and is considered an indicator of the transition between wakefulness and sleep.

While beta waves are associated with active thinking and alertness, delta waves are linked to deep sleep, and theta waves are often connected to light sleep or deep relaxation, alpha waves distinctly represent the state just prior to actual sleep, making them the correct choice in this scenario. The presence of alpha activity is a key marker for drowsiness as it reflects reduced focus and increased relaxation in the brain's activity.