What Is Non-24-Hour Sleep-Wake Disorder?

Rear view of woman sitting alone on bed in room and looking through window at night


Non-24-hour sleep-wake disorder is a type of circadian rhythm sleep disorder. The circadian rhythm is a 24-hour sleep cycle your body follows. People with this condition have a circadian rhythm typically shorter or longer than 24 hours.

However, cases, where the cycle is shorter than 24 hours are rare. Individuals may find that their sleep cycle gradually shifts by one or two hours a day. Weeks of this occurring causes a person's circadian rhythm to become completely desynchronized from the usual 24-hour cycle.

While most people sleep at about the same time every day, a person with this disorder will find that their sleep time is gradually delayed every day. Over time, living with this disorder can lead to health challenges. People with this condition also find it difficult to adhere to regular schedules, which affects work, school, and social obligations.

Symptoms of Non-24-Hour Sleep-Wake Disorder

This condition can look a little different from person to person. Symptoms also range in severity. N24SWD progresses gradually, and so do its symptoms. This means that symptoms of the condition are less severe when it first develops. The most common symptoms of the disorder include: 

  • Insomnia 
  • Daytime sleepiness 
  • Fatigue 
  • Depression
  • Sleeping later and later each night
  • Progressively waking up later every morning

People with N24SWD may not always experience these symptoms. Sometimes their delayed sleep patterns might eventually align with the regular day-night cycle, allowing a person with this condition to get a full night of rest and be up and functioning in the morning.

However, if the condition goes untreated, the cycle continues to shift until it once again becomes desynchronized with the usual 24-hour cycle.


N24SWD is more likely to affect people who are blind. As a result, it's often misdiagnosed in people with sight. Its symptoms are also similar to several other sleeping disorders. To make a conclusive diagnosis, your doctor will take a detailed history of the symptoms you've been exhibiting. They'll also consider your family and medical history.

At the same time, N24SWD isn't necessarily a genetic disorder. Some research points to genetic factors contributing to its development. If you have a history of drug or alcohol misuse, it's also essential to disclose this to your doctor.

You might be asked to keep a sleep diary, recording your sleep and wake times for a couple of weeks. If your doctor suspects another medical condition may be responsible for your symptoms, they'll request additional tests like blood work or a CT scan.

Actigraphy is used to measure sleep-wake cycles. It's used for diagnosing some sleep disorders. It involves you wearing a watchlike device round the clock for a week or two. The device records inactive and active periods of sleep, which can help your doctor establish a pattern of sleep disturbance. 


It's unclear what exactly is responsible for N24WD's development. Over the years, scientists have come up with some plausible theories. What is clear is that light and the way we perceive light plays a significant role in the development of this condition.

In the morning, your body senses that it's bright and wakes you, resetting your body's sleep-wake clock until the next time you sleep. This is why you are more likely to sleep longer in a pitch dark room even if it's already day.


This is the most commonly researched cause of N24SWD. People who are blind don't possess the ability to perceive light. As a result, they'll fail to notice light signals that help your body fine-tune its circadian rhythm.

Some research estimates that around 55%-70% of people who are blind may have N24SWD. However, not all blind people are at risk of developing this disorder. Some blind people retain the ability to perceive light.

Sensitivity to Light 

N24SWD is more likely to occur in people who are blind. However, it can also occur in people with sight in certain cases. One is that people with sight could be hypersensitive or insensitive to light which may affect their circadian rhythms.


Research is still ongoing to find a lasting treatment for non-24-hour sleep-wake disorder. For some people, it's a lifelong condition that has to be constantly managed. Hetlioz (tasimelteon) is the only medication approved by the Food and Drug Administration (FDA) to treat this condition.

Treatment aims at restoring your body's regular sleep-wake cycle. Bright light therapy is another treatment option that may be considered for people with this condition who have light perception. However, this treatment option is only effective for sighted people or people with blindness who can perceive light.

Coping With Non-24-Hour Sleep-Wake Disorder

Maintaining regular sleep-wake times is challenging for a person with this disorder. The inability to perceive light has been identified as a significant causative factor in the development of N24SWD. However, there are other ways to help your body reset its circadian cycle besides light. Some tips to help you achieve this include: 

  • Have a strict sleep schedule: This involves going to bed and waking up at the exact same times daily. You can do this with the help of setting an alarm in the morning to help you wake up and eliminating disturbances at bedtime to help you sleep.
  • Establish a bedtime routine: Work on establishing a relaxing bedtime routine that can help you go to sleep at night. This could either be ensuring there's always white noise playing as you sleep or ensuring that they are no flickering lights anywhere in your bedroom. You can also tape over LED displays.
  • No large meals before bed: Eating a large meal right before bed can disrupt your sleep. Instead, opt for a small snack if you are hungry.
  • Avoid stimulants before bed: Alcohol, nicotine, and caffeine are all stimulants that keep your body wired and can keep you up for hours. It's good practice to avoid consuming anything with stimulants hours before bedtime.

A Word From Verywell 

N24SWD can be a disruptive condition, interrupting your daily functioning and causing problems for you at home, school, or work. If you suspect you or a loved one has this condition, you should speak to a medical professional about it.

5 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. NORD (National Organization for Rare Disorders). Non-24-hour sleep-wake disorder. 2017

  2. Genetic and Rare Diseases Information Center. Non 24 hour sleep wake disorder. November 8, 2021

  3. Emens JS, Eastman CI. Diagnosis and treatment of non-24-h sleep–wake disorder in the blind. Drugs. 2017;77(6):637-650. doi:10.1007/s40265-017-0707-3

  4. U.S. National Library of Medicine. HETLIOZ- tasimelteon capsule. December 10, 2020

  5. Malkani RG, Abbott SM, Reid KJ, Zee PC. Diagnostic and treatment challenges of sighted non–24-hour sleep-wake disorder. J Clin Sleep Med. 2018;14(4):603-613. doi:10.5664%2Fjcsm.7054

By Toketemu Ohwovoriole
Toketemu has been multimedia storyteller for the last four years. Her expertise focuses primarily on mental wellness and women’s health topics.