Infradian rhythms are biological cycles that last longer than 24 hours, occurring over days, weeks, or even months. These rhythms help regulate various physiological processes in living organisms, including hormonal changes, reproductive cycles, and seasonal behaviors. A well-known example is the menstrual cycle in humans, which typically spans about 28 days. Infradian rhythms can also be observed in other species, such as birds that migrate seasonally or bears that hibernate. These rhythms are influenced by environmental factors like light and temperature, helping organisms adapt to changes in their surroundings. Understanding infradian rhythms is important for studying health and behavior in both humans and animals.