Ultradian rhythms are biological cycles that occur more frequently than once every 24 hours, typically lasting from 90 minutes to a few hours. These rhythms regulate various physiological processes, including sleep cycles, hormone release, and alertness levels. For example, during sleep, the body experiences multiple ultradian cycles that alternate between REM sleep and non-REM sleep. These rhythms can influence daily activities and overall well-being. Understanding ultradian rhythms can help individuals optimize their productivity and rest periods. By aligning tasks with these natural cycles, people may enhance focus and reduce fatigue throughout the day.