Sleep physiology is the study of the biological processes that occur during sleep. It involves various stages, including REM (Rapid Eye Movement) and NREM (Non-Rapid Eye Movement) sleep, which cycle throughout the night. During these stages, the body undergoes essential functions such as tissue repair, memory consolidation, and hormone regulation. The brain plays a crucial role in sleep physiology, with structures like the hypothalamus and brainstem regulating sleep-wake cycles. Neurotransmitters, including serotonin and melatonin, help signal the body when to sleep and wake. Understanding these processes is vital for addressing sleep disorders and promoting overall health.