Diurnal rhythm is a term that refers to the biological processes that are synchronized with the 24-hour cycle of light and dark. Some synonyms for the term include circadian rhythm, the body clock, natural sleep-wake cycle, daily cycle, and biological clock. These terms are commonly used in the scientific study of sleep and the circadian rhythm. The diurnal rhythm plays a crucial role in regulating the body's physiology, including hormonal, metabolic, and cognitive functions. Understanding the natural sleep-wake cycle is essential for maintaining optimal health and well-being. Various factors, such as age, lifestyle, and medical conditions, can impact the diurnal rhythm and disrupt sleep patterns.