Originating in the brain stem, and involving other regions of the neurological system, sleep is influenced by factors such as circadian rhythms. Although a person is unaware of much of what happens during sleep, there are four stages that occur in cycles throughout the hours of sleep

There are also developmental alterations regarding the amount of sleep necessary at different life stages, with neonates experiencing a slightly different sleep before circadian rhythms are established, and spending… Like breathing, sleep seems simple and automatic, but the physiological processes involved in sleep involve coordination of multiple body systems and complicated neurological and physical responses.

person — unaware of much of what happens during sleep, there are four stages that occur in cycles throughout the hours of sleep. circadian rhythm — the biological rhythm associated with metabolism, temperature, sleep, and wakefulness. theta wave — an EEG wave that is fast and has variable frequencies. delta wave — EEG brain wave that is slower with higher amplitude.