Doctor's Notes on Sleeplessness and Circadian Rhythm Disorder
A person's circadian rhythm (“biological clock”) regulates several biological processes according to an approximate 24-hour period. The malfunctioning the circadian system causes circadian rhythm disorders. The body systems with the most prominent circadian variations are the sleep-wake cycle, the temperature regulation system, and the endocrine system. Sleep-wake cycle is a type of circadian rhythm disorder and can be categorized into transient disorders (short-term) and chronic disorders. Transient disorders include jet lag, altered sleep schedule due to work hours or social responsibilities, and illness. Chronic biological clock disorders include irregular sleep-wake cycle, delayed sleep-phase syndrome (DSPS), and advanced sleep-phase syndrome (ASPS).
Symptoms of a biological clock sleep disorder include poor concentration, depression, difficulty concentrating, daytime sleepiness, problems falling asleep and staying asleep, non-restorative or poor quality sleep, problems with school or work performance, decreased cognitive skills, headaches, problems with coordination, and digestive problems.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.