REM Sleep: REM sleep stands for Rapid Eye Movement sleep and is a stage of sleep characterized by vivid dreaming, rapid eye movement, and increased brain activity.
NREM Sleep: NREM sleep stands for Non-Rapid Eye Movement sleep and consists of three stages (N1, N2, N3) that involve progressively deeper levels of relaxation.
Circadian Rhythm: Circadian rhythm refers to the internal biological clock that regulates our daily patterns of wakefulness and sleepiness.