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.
Sleeplessness and Circadian Rhythm Disorder Symptoms
Symptoms commonly found in persons with a circadian rhythm disorder related to the sleep-wake cycle can include the following:
Sleeplessness and Circadian Rhythm Disorder Causes
Most of the time, a person's biological clock, or circadian rhythm, is in synchronization with the 24-hour day-night environment. In some individuals, however, the biological circadian rhythm of sleep and wakefulness is out of phase with the conventional or desired sleep-wake schedule.
Causes of biological clock disorders
Sensitivity to zeitgebers ("time givers," or time cues such as light and other environmental cues): This sensitivity may be altered or disrupted, which can be demonstrated under certain conditions. Altered or disrupted sensitivity to zeitgebers is probably the most common cause of the circadian rhythm disorder of the sleep-wake cycle. Patient with blindness may experience difficulty with circadian rhythm, because they lack the light cues through the visual system.
Disrupted pacemaker function: A dysfunction may be present in the internal coupling mechanisms of biological pacemakers, for example, the coupling of the sleep-wake cycle with the temperature cycle.
Environment: Light, higher noise levels, and elevated room temperature are not conducive to good sleep and are important variables to consider in both shift workers and night workers.
Travel: The severity of jet lag is related to the direction of travel and is more frequently seen in individuals traveling in an eastward direction. The number of time zones crossed also has an effect on the severity of jet lag, with most individuals experiencing jet lag if they cross 3 or more time zones. The rate of adjustment is 1.5 hours per day after a westward flight and 1 hour per day after an eastward flight.
Neurological disease: Alzheimer disease is one of the more common examples of neurological disease associated with a circadian rhythm disturbance; however, irregular sleep-wake cycles can also be seen in other neurodegenerative diseases. Sundowning, which is a common phenomenon in persons with Alzheimer disease, is characterized by sleep disruptions with awakenings and confusion.
Shift work: Rapid shift changes and shift changes in the counterclockwise direction are most likely to cause symptoms of a circadian rhythm disorder.
Lifestyle and social pressure to stay up late can exacerbate a circadian rhythm disorder.
Scientists used to think that people were physically and mentally inactive during sleep. But now they know that's not the case. All night long, your body and brain do quite a bit of work that's key for your health. There are two main types of sleep that we cycle in and out of when we rest -- REM (rapid eye movement) and non-REM sleep.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.