Circadian Rhythm Disorders
Circadian rhythm disorders are problems that occur when your sleep-wake cycle is not properly aligned with your environment and interferes with your daily activities.
You have a biological clock that controls the timing of several activities and functions of your body, including when you go to sleep and wake up. This internal mechanism is called the circadian clock. The circadian clock cycles about every 24 hours. These repeating 24-hour cycles are called the circadian rhythm. The control of your circadian rhythm is a function of certain genes in the DNA called circadian clock genes.
Your body tries to align your sleep-wake cycle to cues from the environment that come, for example, when it gets light or dark outside, when you eat, and when you are physically active. When your sleep-wake cycle is out of sync with your environment, you may have difficulty sleeping, and the quality of your sleep may be poor. Disruptions of your sleep-wake cycle that interfere with daily activities may mean that you have a circadian rhythm disorder.
Disruptions in your sleep patterns can be temporary and caused by external factors such as your sleep habits, job, or travel. Or a circadian rhythm disorder can be long-term and caused by internal factors such as your age, your genes, or a medical condition. Symptoms may include extreme daytime sleepiness, insomnia, tiredness, decreased alertness, and problems with memory and decision-making.
To diagnose a circadian rhythm disorder, your doctor may ask about your sleep habits, suggest sleep tests, a diary to track when and how long you sleep, and test the levels of certain hormones in your blood or saliva. Your treatment plan will depend on the type and cause of your circadian rhythm disorder. Treatment may include light therapy, medicines to help you fall asleep or stay awake, or healthy lifestyle changes including steps to improve your sleep habits. If left untreated, circadian rhythm disorders may increase the risk of certain health problems or lead to workplace and road accidents.
Source: National Heart, Lung, and Blood Institute (NHLBI)