An ultradian rhythm is a biological cycle that occurs more frequently than once every 24 hours. These rhythms typically last from 90 minutes to a few hours and can influence various bodily functions, including sleep, hormone release, and alertness. One well-known example is the sleep cycle, which consists of alternating periods of REM and non-REM sleep throughout the night. Ultradian rhythms are essential for maintaining overall health and well-being. Disruptions to these cycles can lead to issues such as fatigue, decreased concentration, and mood disturbances. Understanding and respecting these natural rhythms can help improve productivity and enhance daily functioning.