Which type of brain wave is most prevalent during deep sleep?

Delta waves are the slowest brain waves that are typically observed during the deep stages of sleep, particularly in stages three and four of non-REM sleep. These high-amplitude, low-frequency brain waves (often ranging from 0.5 to 4 Hz) are indicative of the restorative processes that occur during deep sleep, such as tissue growth, repair, and overall rejuvenation of the body. This stage of sleep is crucial for physical health and cognitive function, as it allows for the consolidation of memories and the regulation of essential hormones.

In contrast, alpha waves are associated with relaxed, calm, yet awake states, such as during meditation or daydreaming. Beta waves are involved in alert and active thinking processes, often observed during concentration or problem-solving tasks. Gamma waves are even higher frequency waves linked to cognitive functioning and processing information at a high level. None of these states correspond to the deep restorative sleep characterized by the presence of delta waves.