What EEG pattern is most commonly associated with sleep?

The EEG pattern most commonly associated with sleep is delta activity. During sleep, especially in the deeper stages (NREM sleep stages 3 and 4), delta waves are prominent on the EEG. Delta waves are characterized by their low frequency (typically 0.5 to 4 Hz) and high amplitude, reflecting the brain's state of restorative processes during sleep.

In contrast, beta activity is typically associated with alertness, active concentration, and mental engagement. Alpha waves, while present during relaxed, wakeful states with closed eyes, are not dominant during sleep. Gamma waves, which are related to cognitive functions and high-level information processing, occur during wakefulness and intense mental activity rather than during sleep phases. Hence, delta activity is the correct choice as it is directly linked to the sleep cycle, specifically in the deeper stages of sleep where significant restorative functions take place.