Melatonin: A hormone produced by the pineal gland that plays a key role in regulating sleep-wake cycles. It is often referred to as the "sleep hormone."
Circadian Rhythm: The internal biological clock that regulates various physiological processes, including sleeping and waking patterns. It follows a 24-hour cycle.
REM Sleep: Rapid Eye Movement (REM) sleep is one of the stages of sleep characterized by rapid eye movements, vivid dreams, and increased brain activity. It is associated with memory consolidation and learning.