What is a sleep cycle?
A sleep cycle is the recurring pattern of alternating rapid eye movement (REM) sleep and slow-wave sleep, also known as the deep sleep stage. This cycle repeats four to six times per night, with each cycle lasting 80 to 100 minutes (National Heart, Lung, and Blood Institute, 2022).
A complete sleep cycle consists of three non-REM (NREM) stages followed by REM sleep (Colten & Altevogt, 2015). The cycle plays a vital role in sleep quality, as it regulates hormone production, muscle repair, and memory consolidation. Irregularities in the sleep schedule can lead to sleep deprivation, affecting the immune system and cognitive function.
Sleep spindles, bursts of brain activity during NREM sleep, contribute to learning and memory retention (Cowan et. al., 2020). Disruptions, such as sleep apnea and obstructive sleep apnea, prevent the body from achieving enough sleep and a healthier sleep cycle. Maintaining a good night's sleep is essential for preventing sleep disorders and ensuring proper progression through each deep sleep phase.










