What EEG pattern is typically observed during deep sleep?

During deep sleep, the EEG pattern predominantly consists of delta waves. These waves are characterized by their slow frequency (typically ranging from 0.5 to 4 Hz) and high amplitude. Delta waves are crucial for the restorative aspects of sleep, as they are believed to reflect the body's deep restorative processes. This stage of sleep is where the body undergoes significant repair and rejuvenation, and it is essential for overall health and well-being.

Theta waves are more associated with light sleep and the transition between wakefulness and sleep, while alpha waves are typically present during relaxed, awake states, often when a person is calm but alert. Fast beta waves are linked to active thinking and concentration, occurring when a person is awake and engaged. Hence, the presence of delta waves during deep sleep distinctly indicates the brain's transition into a restorative sleep state, making it the correct choice for this question.