Circadian Rhythm Sleep Disorders

If you’ve done research about sleep, you’ve probably come across the term “circadian rhythm.” While it sounds like a complex concept, in fact, a person’s circadian rhythm is really just their internal clock. This clock helps regulate our sleeping and align it with daytime and nighttime.

For some people, this internal clock becomes thrown off and is no longer in alignment with light and dark. When this happens, a person may have a hard time falling asleep or waking up when they need to. When this persists, it is considered to be a circadian rhythm sleep disorder. Circadian rhythm sleep disorders can happen for many different reasons, and they can have significant impacts on a person’s wellness and ability to get good sleep.

In this guide, we’ll help you understand the critical details about circadian rhythm sleep disorders including what they are, their causes and implications as well as their diagnosis and treatment.

What Are Circadian Rhythm Sleep Disorders?

To understand circadian rhythm sleep disorders, it’s first necessary to understand the circadian rhythm. In short, it is the body’s way of responding to changes from light to dark during the course of one day. In response to light, the brain produces signals that affect the production of hormones in the body. These signals and hormones influence how you feel and your ability to sleep and wake up.

When a person’s circadian rhythm is well-aligned, they naturally start getting more tired and sleepy as the night gets dark, and then they feel refreshed and with more energy when they wake up in the morning. Of course, every person is different, and it is possible to be more a morning or evening person without having a disrupted circadian rhythm. In general, it’s not a problem to vary from a strict light-dark sleeping schedule if you are able to maintain consistency in your bedtime, can get to bed or wake up earlier if need be, and if you can adjust to a new routine without major sleeping problems.

If you aren’t able to do those things, it may be an indication of a circadian rhythm sleep disorder. This disorder may cause you to fall asleep when you don’t want to or make it nearly impossible to get to sleep or wake up according to your needed schedule.

There are several different types of circadian rhythm sleep disorders that include:

  • Jet lag type/disorder: this is a disruption of the circadian rhythm caused by traveling across multiple time zones in rapid succession (such as on an airplane).
  • Shift work type/disorder: in this type, the disruption is caused by the fact that a person’s work requires them to have a schedule that puts their sleeping out of alignment with the normal day-night timeline of the day. Night shift workers often struggle with this type.
  • Delayed sleep phase type/disorder: this is associated with night owls, who stay up late and wake up late and can’t fall asleep earlier even if they want or need to.
  • Advanced sleep phase type/disorder: the reverse of delayed sleep phase type, people with this type fall asleep and wake up early even if they want or need to be up later.
  • Non-24 hour sleep-wake syndrome: this is a more rare type but involves a sleep-wake cycle that varies from day-to-day. A person is thus not able to establish consistency in their circadian rhythm with the day’s progression.

What Are the Symptoms of Circadian Rhythm Sleep Disorders?

Lack of sleep and the problems associated with poor sleep are all potential symptoms of circadian rhythm sleep disorders. Without quality sleep, people can be physically and mentally fatigued. They may have slower reaction times, shorter attention span, and a tendency toward irritability. Drowsiness during the day can put people at heightened risk of accidents (such as from auto collisions or falls).

Because the circadian rhythm is involved in the body’s processes of regulating hormones and temperature, other symptoms can arise when these disorders are prolonged. For example, nausea, depression, irritability, and general malaise are all possible symptoms. There can also be cardiovascular impacts depending on the specific person and disorder.

Symptoms may become exacerbated if routines are regularly changing or with more pronounced travel (e.g., worse jet lag). Taking medications to try to sleep can also interfere with the process of correcting the circadian rhythm if someone becomes dependent on them to try to sleep.

What Are the Causes of Circadian Rhythm Sleep Disorders?

Often, circadian rhythm sleep disorders are caused by changes to a person’s routine or environment. These external causes can include:

  • Travel/jet lag: when you move quickly across multiple time zones, especially when flying from west to east, your body does not have time to adjust to the new light-dark cycle in the place where you have just traveled. This can throw off your circadian rhythm. This can be a challenge for people who regularly travel but may affect people who are only traveling for a shorter duration.
  • Shift work: when someone has to work nights, then they are functionally required to have their sleep-wake cycle misaligned with the light of the day. While some night shift workers are able to establish a routine that allows them to get enough sleep, many find that this is impossible. This is especially the case if their shifts are irregular, if they are not able to find a dark and comfortable place to sleep during the day, and/or if other obligations require them to cut short their sleeping time.
  • Sleep-wake inconsistency: experts usually recommend going to bed and waking up at the same time every day because not doing so can create problems with alignment of your circadian rhythm.
  • Excessive bed rest: if you are confined to bed (such as because of an injury or hospitalization) and do not have the ability to be exposed to daylight, it can interfere with your circadian rhythm.
  • Some medications: the use of some medications, especially their regular use, may prevent consistency in getting to bed or waking up and create sleep-wake cycle disruptions.

There are also some causes of circadian rhythm sleep disorders that are internal. For example, brain damage, such as from a stroke or injury, can prevent a person from being able to properly regulate their sleep-wake cycle.

What Are the Health Risks of Circadian Rhythm Sleep Disorders?

As discussed in the section about symptoms, people with circadian rhythm sleep disorders often have poor quality sleep. This can cause them to feel unwell, irritable, fatigued, and lacking in concentration. This can affect a person’s work or studies as well as their personal relationships. Many activities -- such as driving or home repair tasks -- can also become much more dangerous when a person is sleep deprived. The risks of accidents and injuries is generally higher when people are lacking in sleep such as with circadian rhythm sleep disorders.

How Are Circadian Rhythm Sleep Disorders Diagnosed?

The diagnostic process for circadian rhythm sleep disorders is normally straightforward. Diagnosis starts with a health history that reviews your overall health and what you have been experiencing with your sleep. This may be coupled with a physical exam.

The doctor will use the information from the health history discussion to try to identify if you have a circadian rhythm sleep disorder. In many cases, the doctor may need more information, in which case, he or she may ask you to maintain a sleep journal for a period of time in which you track things like the times when you go to bed and wake up each day.

In rare cases, a doctor may prescribe a sleep study, perhaps including an overnight visit at a specialty sleep center, but this is normally not necessary for circadian rhythm sleep disorders.

How Are Circadian Rhythm Sleep Disorders Treated?

Most circadian rhythm sleep disorders can be treated effectively although treatment often takes some time and effort on behalf of the patient. The most common aspect of treatment is changing sleep behaviors. This is especially true if the cause of the problem is external. Improving sleep hygiene and habits as part of treatment for circadian rhythm sleep disorders can include:

  • Setting firm times for going to bed and waking up: this involves putting strict timeframes for the sleep-wake cycle. The goal of this is to create consistency in your routine so that your body and circadian rhythm can become aligned with natural light. Experts usually encourage sticking to this routine even during weekends or during vacations when you may have different schedules or demands during the day.
  • Limiting non-sleep bedtime: hanging around in bed after you wake up or before you go to bed can reduce the association between your bed and sleep. That association can play a powerful role in encouraging a consistent sleep-wake pattern.
  • Regulating light exposure: because the circadian rhythm is predicated on responses to light, making sure that there is proper light exposure can help limit disruptions. For example, shift workers can make a point of getting some light exposure when awake and reduce light exposure when they are done working and getting ready for bed. Similarly, limiting exposure to screens (phones, tablets, computers) close to bedtime may help to prevent disruptions from abnormal light exposure.
  • Improving sleep environment: making sure that your bedroom is dark, quiet, and has a comfortable mattress and pillows can help create the conditions needed for you to fall asleep more easily and thus wake up when you need to.
  • Adjust the sleep-wake cycle: if a person’s sleep-wake cycle naturally tends earlier or later, one lifestyle change may be to try to adjust their daily activities to this schedule rather than trying to adjust their sleep-wake cycle.
  • Planning ahead for travel: if a person is at risk of a circadian rhythm sleep disorder from jet lag, they may find it helpful to plan ahead for how to manage the time zone change when they fly. This may include beginning to re-align the body’s internal clock a few days before traveling or planning a travel schedule that allows time to adjust to a new sleep schedule more easily.

What Medications Are Available for Circadian Rhythm Sleep Disorders?

In addition to lifestyle and habit changes, there are some medical treatments for circadian rhythm sleep disorders. Some examples include:

Sleep aids

These are drugs that are designed to help you fall asleep. Some are available over-the-counter while others require a prescription from a doctor. These drugs do not really re-adjust your circadian rhythm, but they can help in the short term to boost your sleep and in some cases to help reset your sleep schedule so that you can establish a more consistent sleep-wake pattern.

Stay-awake aids

These drugs, which can range from simple things like caffeine to prescription medications like modafinil, are designed to help you be awake and alert. They may help address daytime sleepiness or to help someone stay awake until their bedtime aligns with the day’s light (such as when traveling and dealing with jet lag).


Melatonin is a hormone that is involved in making the body feel sleepy. When the circadian rhythm is aligned, the body starts to produce melatonin during the evening so that you feel sleepy and can go to bed without problems. Some people with sleeping issues take supplements of melatonin. There is limited hard evidence from research studies about the effectiveness of melatonin or about its use over the long-term.

While it is usually well-tolerated, it is advisable to talk with a doctor before starting to take melatonin supplements. Tasimelteon is similar to melatonin and is designed to be taken at night. This drug, though, has had reports of side effects of very abnormal dreams.

It is important to talk with a doctor or health professional before beginning to take any medications such as these or others to try to manage sleeping problems. Your doctor will be best able to discuss the benefits and risks of any specific drug in your unique case.

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