Calculating sleep cycles involves determining the duration and timing of the distinct stages of sleep a person experiences throughout the night. These stages, typically repeating in cycles of approximately 90 minutes, include light sleep, deep sleep, and rapid eye movement (REM) sleep. Understanding these patterns can be achieved through various methods, including sleep diaries, actigraphy (wrist-worn movement sensors), and polysomnography (sleep studies conducted in a laboratory setting). For instance, an actigraph might reveal that a person spends an average of 20 minutes in REM sleep during each cycle.
Optimizing sleep timing based on these cyclical patterns can lead to more restful and restorative sleep. Waking up during lighter sleep stages can make one feel more refreshed, while interrupting deep sleep can result in grogginess. This knowledge has practical applications in scheduling alarms, planning naps, and addressing sleep disturbances. Historically, understanding sleep cycles developed alongside broader advancements in sleep science throughout the 20th century, evolving from initial electroencephalography (EEG) observations to more sophisticated monitoring technologies and analytical approaches.
