What Causes Circadian Rhythm Disorders?

May 8, 2024

Circadian rhythm disorders, also known as circadian rhythm sleep-wake disorders, are a category of several different conditions that disrupt the body's internal twenty-four-hour clock called the circadian rhythm. Some of the most common forms of circadian rhythm disorders are shift work disorder, jet lag, advanced sleep phase syndrome, delayed sleep phase syndrome, and non-24-hour sleep-wake disorder. Circadian rhythm disorders can affect anyone of any age. Possible indicators of these disorders include daytime sleepiness, difficulty concentrating, difficulty with making decisions and thinking clearly, and low performance at work or school. Patients may feel generally unwell, and some may become depressed or irritable. In an effort to resolve circadian rhythm disorders, some patients may misuse alcohol, sleeping pills, or stimulants. Sleep specialists typically use overnight and daytime sleep studies to diagnose circadian rhythm disorders, and sleep diaries and actigraphy may also aid in reaching a proper diagnosis. Treatment options depend on the patient's specific disorder and may include medication, behavioral therapy, bright light therapy, and chronotherapy.

Some of the more frequent causes of common types of circadian rhythm disorders are outlined below.

Time Zone Changes And Jet Lag

Time zone changes and jet lag can both cause disruptions to an individual's circadian rhythm, and jet lag is a recognized type of circadian rhythm disorder. The time zone changes that occur when a patient travels east result in what is known as an advanced sleep cycle. This type of sleep cycle is set in motion when both waking and sleeping times are made earlier than they are in the patient's home time zone, and it often results in much more severe jet lag than patients who travel west might experience. Experts suggest it may take up to one day of adjustment time for each time zone the patient has crossed. For example, if an individual crosses five time zones, they may need up to five days to fully adjust to the time in the new location. Older people and individuals with chronic medical conditions may need several weeks to adjust to a new time zone.

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Alzheimer's Disease

Alzheimer's disease is a major cause of circadian rhythm disturbances, and these disturbances may begin years before memory loss is observed. In the early stages of Alzheimer's disease, patients often sleep more than they normally would, and they might be disoriented upon waking. As the disease advances, the patient may start to sleep during the daytime, remaining awake at night. In moderate to severe Alzheimer's disease, patients tend to doze irregularly during the day and night instead of sleeping for long blocks of time at once. These disruptions to the patient's circadian rhythm often increase the risk of both nighttime wandering and agitation during the evening hours (sometimes known as sundowning). Studies have suggested Alzheimer's patients might gradually lose their ability to stay asleep as the disease worsens. They may need sleep medications, antidepressants, and other medications to promote a healthier sleep-wake cycle.

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Issues With Mental Health

Issues with mental health, including depression, obsessive-compulsive disorder, anxiety, bipolar disorder, and schizophrenia, are all associated with disruptions in an individual's circadian rhythm. Researchers are still debating whether the issues with mental health cause the circadian rhythm disturbances or whether the circadian rhythm disorders themselves could trigger some types of mental health issues. Patients with mental health issues may have their circadian rhythm impacted in various ways. For example, some patients with depression will sleep longer than normal for them, and other depressed individuals may struggle with insomnia. Many patients with bipolar disorder who are experiencing an episode of mania could also struggle with insomnia and stay up for long periods at night. Normally, treatment for the mental health condition itself can help in resolving circadian rhythm problems, and patients may benefit from a combination of medication and behavioral therapy. Keeping a sleep diary could be useful for patients with mental health conditions as it allows them to notice patterns in their sleeping and waking cycles. This information may be helpful to the patient's healthcare team as they work to design an appropriate treatment plan.

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Shift Work

Shift work may cause an employee to have to work at odd hours of the day or night, and some shift workers may have to work through the night for years. Circadian rhythm disorders are so common among shift workers that the term 'shift-work sleep disorder' was coined to describe the particular disruptions that plague these employees. In particular, employees who work on a rotating schedule pattern face an especially high risk of developing this type of sleep disorder. While those who work the night shift regularly may be able to adjust their sleep patterns, rotating work schedules don't allow an individual to have a regular time frame for their work, and this can result in both insomnia and daytime sleepiness. To reduce the risk of this type of circadian disruption, individuals should aim to have a regular working schedule whenever this is possible, and they should eat healthy meals at regular intervals to help reset their body clock. If necessary, a sleep specialist can help shift workers with getting higher-quality, more restful sleep.

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Changes In Sleeping Routine

Changes in one's sleeping routine may gradually lead to the development of a circadian rhythm disorder. For example, if an individual stays up all night for one or more nights in a row to study for an exam, they may experience daytime sleepiness, and it may start to feel as if day and night have been reversed. To prevent changes in sleeping routine from getting out of hand, sleep specialists advise that patients practice good sleep hygiene. This includes keeping the bedroom dark and cool and not using the bedroom for activities like watching television or going online. Going to bed and waking up at the same time each day, including on the weekends, is also recommended. Exposure to bright light soon after waking up in the morning can help with regulating sleeping patterns, and patients should avoid the blue light from electronic devices at least one hour before bedtime.

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