What is Non-24 Hour Sleep Wake Disorder?

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woman struggling to sleep with clock on wall and sunlight outside

Non-24 Hour Sleep Wake Disorder is a condition in which an individual’s internal body clock, also known as circadian rhythm, will not coincide with a 24-hour day. This means the person won’t feel tired at the same time each night (like most people do) and could find themselves falling asleep later and later, without regard for the time of day or not. This disorder can cause multiple issues, from insomnia to daytime drowsiness. Even though it primarily affects blind people, sighted people can also experience this disorder.

To learn more about Non-24 Disorder, I consulted with Dr. Peter Polos, a sleep medicine specialist at Sleep Number, who gave input on how this disorder affects sleep patterns and some ways it can be managed.

What is a Circadian Rhythm and Why is it Important?

Non-24 disrupts your circadian rhythm, which is your body’s 24-hour internal clock. This clock controls your sleep-wake cycle, but it’s also responsible for a host of other processes, like preparing your body for times when you’re active, sleeping, or need to eat.

Your sleep-wake cycle is closely related to your environment’s external light-dark cycle. For example, daylight tells your internal clock it’s time to get up. When the sun sets, the dark tells your body it’s time to sleep.

Our bodies are designed to sleep a certain number of hours at certain times, so when there’s a disruption in your circadian rhythm, it makes it more difficult to sleep . Since your body repairs itself when you’re asleep, these disruptions can put you at a greater risk for various diseases, such as cancer, diabetes, heart disease, and depression.

Dr. Polos says these disruptions can cause you to feel sluggish and make it difficult to stay awake and concentrate. He also says that your eating habits, digestion, and other bodily functions can be negatively impacted. This is because, in addition to telling your body when it’s time to eat, your circadian rhythm optimizes physiological functions, such as digestion.

Your circadian rhythm can get out of sync for a variety of reasons, other than non-24. These include using light-emitting devices at night (which can confuse your internal clock), jet lag, work shift changes, and genetic mutations that impact your internal clock.

What is Non-24 Hour Sleep Wake Disorder?

Dr. Polos explains that Non-24 “is a neurological sleep disorder in which a person’s sleep-wake cycle is longer than 24 hours. That means the person is unable to adjust their sleep-wake cycle to the length of the day, and sleep time gradually progresses around the clock.”

Signs and symptoms of Non-24 include:

  • Insomnia
  • Grogginess and inability to focus during the day
  • Irregular sleep patterns
  • Depression

If you’re experiencing any of these symptoms, consider talking to your doctor to find out if it’s related to Non-24.

Who is at Risk for Non-24 Hour Disorder?

Non-24 affects 55-70% of totally blind people (those who can’t perceive light). Since the body uses light as a signal to set its internal clock to a 24-hour day, the inability to perceive light greatly affects one’s internal clock. However, Non-24 isn’t a disorder that only affects blind people.

Sighted people who experience Non-24 tend to develop it in their teens, and they tend to be males. Blind people can develop it at any age.

According to Dr. Polos, sighted people with Non-24 experience a reduced sensitivity to light, which drives the circadian rhythm. He says this can happen as a result of:

If you suspect you have Non-24, Dr. Polos recommends speaking to a sleep specialist. He says the disorder is complex and can be misdiagnosed as another circadian rhythm disorder. An evaluation from a specialist can help determine the right treatment for you.

Managing Non-24 Hour Sleep Wake Disorder

There’s no cure for Non-24, but you can manage it. Here are a few practices to help you do so:

  • Set a regular schedule for going to bed, getting up, and eating meals
  • Exercise in the morning
  • Take a cold shower in the morning
  • Keep a sleep journal for at least two weeks to detect the Non-24 pattern
  • Take melatonin at least two hours before bedtime
  • Be exposed to bright light therapy or natural light in the morning
  • Take prescribed medication, but be aware that it can cause you to feel tired during the day
  • Maximize your sleep time by using a mattress that works best for your height, weight, and preferred sleeping position

Dr. Polos says it’s vital you establish a regular sleep/wake schedule that you abide by every day, even on weekends. He says that straying from this routine can disrupt your circadian rhythm.

Final Thoughts

Having Non-24 doesn’t mean you’ll never feel rested again. Sticking to a regular sleep/wake schedule, exercising in the morning, and speaking to a sleep specialist are steps you can take to manage this disorder. Be sure to talk to your doctor if you believe you may have Non-24.

Victoria Wildhorn

Victoria is a Sleep Health Content Specialist at Mattress Clarity who creates and shares sleep resources, especially for those with health conditions, to help improve their sleep. A South Florida native, she understands the concerns of hot sleepers, as well as the importance of creating a sleep-conducive environment at night. Victoria enjoys connecting with medical specialists who lend their expertise on various health-related topics as they relate to sleep, and is always happy to share our best tips for each individual’s sleeping needs!