Non-24-Hour Sleep-Wake Disorder (Non-24)

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The internal biological clock of the human body medically referred to as the circadian rhythms, is responsible for keeping us synchronized with the outside environment. When nighttime arrives, and you are exposed to darkness, a series of events are triggered. This causes us to feel tired.

Certain functions in the body changes. When the sun comes up, and you are exposed to light, changes occur once again, and a trigger is sent to the brain to wake up. This is how circadian rhythms usually work, but for some people, things are not as simple.

Non-24 is a type of Circadian Rhythm Sleep Disorder. People with this disorder experience a disturbance with their internal biological clock, leading to a change in their 24-hour sleep-wake cycles. The disorder causes the person to struggle to fall asleep at the right times when night falls and wake up when the sun comes up.

Causes Non-24

Non-24-Hour Sleep-Wake Disorder is most commonly found in blind people, in which case the inability to be exposed to the normal light-dark cycles of each day causes the person to develop the disorder and experience the various symptoms associated with this sleep disorder. Even though the condition is mostly found in blind people, it should be noted that this does not mean that only blind people can be affected by Non-24-Hour Sleep-Wake Disorder.

In patients who have normal sight, the condition can be caused by poor sleeping habits. Not being exposed to daylight at the right times, for example, can contribute to the development of Non-24. This can happen when a patient spends too much time in a dark room. Substance abuse is also considered a possible contributing factor to the development of this sleep disorder. Conditions such as personality disorders and psychiatric disorders have also been linked to this condition.

Other risk factors associated with Non-24 include being diagnosed with dementia, having suffered a brain injury, or suffering from mental retardation.

Symptoms of Non-24

sleeping late at night

Non-24-Hour Sleep-Wake Disorder can have a significant impact on a patient’s life, making it essential for individuals to recognize the symptoms and opt for appropriate treatment options to help them gain back a better synchronization with the day-night cycles of their external environment. Many of the symptoms that are associated with Non-24 are also found in other sleep disorders, but there are some distinct differences that patients may notice.

  • Patients with Non-24-Hour Sleep-Wake Disorder tend to experience cyclic insomnia.
  • The condition tends to make a patient fall asleep somewhat later every night.
  • There may be periods of “reset” where the person is able to fall asleep at a normal time, but the symptoms gradually start to appear again as the patient goes through the cycle.
 The majority of patients who experiences Non-24 tend to complain about being excessively sleepy during the daytime.


The diagnosis process for Non-24 is often considered difficult and should be conducted by a professional who has experience in working with patients diagnosed with the condition in the past.

Many patients with Non-24-Hour Sleep-Wake Disorder is misdiagnosed when they are examined by a health professional that does not have an adequate amount of experience with this particular sleep disorder. Opting for an appointment at a sleep doctor will be able to provide a more accurate diagnosis as compared to making an appointment with a general practitioner.

There are different types of diagnostic tests and tools that can be useful in providing an accurate diagnosis of Non-24. In most cases, the first step toward a diagnosis will be to ask the patient to keep a sleep diary with them. The sleep diary should be used on a daily basis to record sleep times. This diagnostic tool will offer both the patient and the health professional important data regarding the sleep-wake cycles of the patient. The health professional will look for cycling sleep-wake patterns in the patient’s sleep diary to determine if Non-24 would be the most appropriate diagnosis.

Other tools are also available to provide more in-depth data and more accurate readings of the patient’s sleep-wake cycles. An actigraph is a very useful diagnostic tool. This watch-like device is worn on the patient's wrist for a specified period of time. The device will record the activity level of the patient and also provide an accurate analysis of their sleep-wake cycles.

actigraph device

Since Non-24 can mimic the symptoms of other sleep disorders and the other way around, it is essential that the possible presence of other sleep-related conditions be ruled out prior to a final diagnosis. This is where a polysomnogram comes in handy. This is an overnight sleep study that monitors the patient’s sleep during a single night. A polysomnogram will help a health professional determine if Non-24-Hour Sleep-Wake Disorder is the appropriate diagnosis and if any other sleep disorders may be present in the patient.

Non-24 Treatment

A number of treatment protocols have been proven effective in assisting a patient in relieving the symptoms caused by Non-24. All treatments are focused on helping to resynchronize the biological clock, or circadian rhythms, of the patient with the normal day-night cycle that occurs in each 24-hour period.

One of the most common types of treatments used in patients with Non-24  is Melatonin based sleeping pills. This ingredient is used in many dietary supplements. Melatonin is naturally found in the human body and is released at nighttime in patients with normal sleep-wake cycles, causing the patient to feel sleepy. When a patient with Non-24 is prescribed Melatonin, it can assist with restoring this normal sleep-wake cycle by forcing them to feel sleepy at the right times.

Other treatment options are also available. Phototherapy can be a useful option for patients that have been diagnosed with Non-24, but this option only works in patients who are not blind.

Tasimelteon, a medication classified as a melatonin receptor agonist, is a pharmaceutical option that has been approved by the FDA for the treatment of Non-24 in 2014. This is still a relatively new option but holds the potential to possibly assist a patient, especially when blind or when other treatment protocols have proven ineffective.

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