Circadian Rhythm Sleep Disorders

What are circadian rhythm disorders?

Circadian rhythm disorders are conditions that disrupt or affect your body’s natural sleep-wake cycle. These disruptions affect how well you sleep, when you sleep and how you function while awake. They're also known as “circadian rhythm sleep disorders” or “circadian rhythm sleep-wake disorders.”

“Circadian” comes from Latin and means “around the day.” The circadian rhythm tells your body when to sleep and wake. It involves multiple components and processes in systems throughout your body. Most people’s circadian rhythms are automatic, and their bodies follow them without any problems. But if you have a circadian rhythm disorder, that process may not work as it should.

Types of circadian rhythm disorders

• Jet lag disorder. You’ve recently traveled to a different time zone, which takes you out of sync with the day/night schedule you’re used to.
• Shift work sleep disorder (SWSD). You have trouble adjusting your circadian rhythm to your work schedule. You’re more prone to this if you work night shifts.
• Delayed sleep-wake phase disorder (DSWPD). Your sleep/wake schedule is much later than the average person. It’s more common in children and teenagers.
• Advanced sleep-wake phase disorder (ASWPD). You go to bed earlier and wake earlier than the average person.
• Irregular sleep-wake rhythm disorder (ISWRD). Your sleep and wake times happen at unpredictable, disorganized intervals. This usually happens to people with dementia or other degenerative brain diseases.
• Non-24-hour sleep-wake rhythm disorder (N24SWD). Your circadian rhythm is predictable, but it isn’t 24 hours like most people’s. It’s usually longer, but it could be shorter.

Other circadian rhythm disorders or disruptions different from those listed above are also possible. In those cases, experts classify them as “circadian sleep-wake disorder not otherwise specified.”

How common are circadian rhythm disorders?

Most circadian rhythm disorders are rare. Experts estimate they affect about 3% of people worldwide.

There are two key exceptions to this: jet lag and shift work sleep disorder. Jet lag is common and expected for travelers flying to a destination with at least a two-hour time difference. Shift work sleep disorder affects about one-third of people who work shifts during nighttime hours.

What are the symptoms of circadian rhythm disorders?

The symptoms of circadian rhythm disorders revolve around sleep and waking. They specifically involve details about your sleep cycle or how your body naturally anchors itself to day and night.

The symptoms of these various disorders vary depending on the particular disorder. You may have:

• Trouble falling asleep (insomnia).
• Difficulty staying asleep.
• Trouble falling back asleep during the middle of the night or early in the morning.
• Waking up earlier than you want or plan.
• Trouble walking up (sleep inertia) or unpredictable sleep-wake times.
• Sleepiness during the day, which can lead to hypersomnia.
• Needing to nap during the daytime.
• Fatigue.
• Headaches.
• Depression, irritability and other issues due to lack of sleep.

What causes circadian rhythm disorders?

People with circadian rhythm disorders often have differences in their body’s natural “clock” or related processes. Sometimes, that involves a problem in part of your brain.

Inside your brain is a structure called the hypothalamus. The hypothalamus is home to a specific cluster of brain cells (neurons) called the suprachiasmatic nucleus (SCN). It’s your body’s “clock.” Without any outside cues, the human body generally runs on a sleep-wake cycle that lasts a little over 24 hours.

Circadian rhythm disorders can happen because of:

• Brain damage or disruptions in brain activity. Examples include degenerative brain diseases, head injuries and infections that cause encephalitis.
• Vision impairments. The SCN has a direct connection to your eyes. That’s why daylight is a key set point. Likewise, people with damage to their eyes, retinas or optic nerves are more likely to have circadian rhythm disorders.
• Travel. Jet lag is a key circadian rhythm disorder that happens entirely due to advances in modern technology. We can travel faster than our bodies know how to adjust.
• Work. People who begin working overnight shifts may experience circadian rhythm disorders because of the change.
• Unknown. Some people have circadian rhythm disorders for reasons that experts can’t explain or find a cause for.

What are the risk factors for circadian rhythm disorders?

Several potential risk factors can make circadian rhythm disorders more likely to develop. You can manage some of them, but others aren’t manageable.

They include:

• Age. Children and teens are more likely to develop delayed sleep-wake phase disorder. Older adults (especially those over 60) are more likely to have advanced sleep-wake phase disorder.
• Genetics. You can inherit certain sleep traits and characteristics from one or both parents. There’s also research that links certain genetic mutations to a higher risk of some circadian rhythm disorders.
• Direction of air travel. Traveling east (which advances your sleep cycle) tends to cause more severe jet lag than traveling west (which delays your sleep cycle).
• Shift timing changes. Shift workers who are changing shifts are more likely to experience issues if they move to an earlier shift than what they’re used to.
• Neurodevelopmental differences. People with attention-deficit/hyperactivity disorder (ADHD) or autism spectrum disorder, may be more prone to developing circadian rhythm disorders.

What are the complications of circadian rhythm disorders?

Circadian rhythm disorders can vary widely. Some have minimal effects, while others cause major disruptions. Some examples include:

• School or work difficulties. People with a circadian rhythm disorder may have trouble with school or work schedules.
• Other sleep problems. People with a circadian rhythm disorder may develop other sleep issues or sleep disorders, especially chronic insomnia.
• Substance use. People with a circadian rhythm disorder may try over-the-counter sleeping pills, alcohol or drugs (prescribed or unprescribed) to help them sleep. That can lead to developing alcohol use disorder or substance use disorder.
• Accidents and injuries. People with a circadian rhythm disorder may have daytime sleepiness. That can lead to accidents or injuries.

How are circadian rhythm disorders diagnosed?

To receive a diagnosis of a circadian rhythm disorder, you must have the symptoms for at least three months (the only exception is jet lag disorder, which has no time requirement). A healthcare provider can diagnose a circadian rhythm disorder using a combination of methods. They include:

• Questionnaires, medical history and talking to you. This includes asking questions and gathering information about your symptoms, sleep habits and any changes or issues affecting your work or personal life.
• A physical and neurological exam. These look for signs or symptoms of any condition that could be causing or contributing to circadian rhythm issues.
• Lab testing. These include saliva, blood and urine tests. These look for and check levels of hormones and other markers that might indicate the cause or type of circadian rhythm disorder you have.
• Imaging scans. Computed tomography (CT) and magnetic resonance imaging (MRI) scans may help diagnose conditions that could be causing or contributing to a circadian rhythm disorder.
• Sleep logs. Your provider may ask you to keep a sleep log or diary to track your sleep behaviors.
• Actigraphy. This test involves a wearable, motion-sensitive device. Healthcare providers can use it to track and analyze your activity patterns. Many of these devices look like a wristwatch, and you wear them like one. Your provider may ask you to wear one 24 hours a day for a few days or as long as two weeks.

Other tests may also be possible depending on your symptoms and what your healthcare provider suspects. Your provider can tell you more about the specific tests they recommend and why they think these tests will be helpful.

How are circadian rhythm disorders treated?

The treatments for circadian rhythm disorders vary depending on the specific disorder and your personal circumstances. Treatments may involve one or more of the following:

• Adjust your lighting.
• Take supplemental melatonin (a sleep-regulating hormone your body produces naturally) or medications that work similarly, after talking with your healthcare provider.
• Adjust sleep-related behaviors.

Adjust your lighting

The SCN connects directly to your retinas. That connection is why daylight has such a strong effect on most people’s circadian rhythm.

If you’ve been to the lighting section at a big-box hardware store, you’ve likely noticed that lightbulbs come in many different shades of white. There’s blue white and yellow white, warm white and cool white. If you have circadian rhythm disorders, you can adjust the brightness and color temperature of the light around you to help manage your sleep/wake cycle.

Generally, bright light helps you wake up and dim light helps you wind down. So, you might try putting bright lights on in the morning, upon waking. And as you get ready for bed, dim the lights.

You can also adjust the color of the lights around you. Cooler temperatures of light have more blue in them (think sky blue). Your brain is most sensitive to blue light, and you can use this to your advantage to help your sleep. Try to limit the use of cool (blue) lights to daytime. Then, as evening nears, use warmer, yellow light.

Screens like televisions, computer monitors and smartphones emit blue light. Adjusting their screen color settings and limiting their use before bedtime may help you sleep.

Medications

Your body makes a hormone, melatonin, to regulate your circadian rhythm and make you sleepy. Work closely with your healthcare provider to determine the dose of melatonin that’s right for you. Melatonin supplements are available over the counter, and there are prescription medications that work similarly to melatonin. Examples include tasimelteon or ramelteon. Healthcare providers often prescribe these for circadian rhythm disorders.

Sleep behavior adjustments

“Sleep hygiene” is the term healthcare providers often use to describe behaviors that can improve sleep quality and quantity. Sleep hygiene behaviors include:

• Set and keep a consistent sleep schedule.
• Gradually move your bedtime.
• Make time to get enough sleep.
• Have a bedtime routine.
• Avoid bright lights and electronic screens close to bedtime.
• Avoid alcohol and meals, and limit fluid intake close to bedtime.
• Use your bedroom for sleeping or intimate activities only.

Can circadian rhythm disorders be prevented?

Many circadian rhythm disorders happen unpredictably or for reasons you can’t control. You may be able to reduce your risk of developing some of them. One circadian rhythm disorder, jet lag, is considered a normal consequence of traveling across time zones by airplane.

But some causes of circadian rhythm disorders are impossible to prevent. This is especially true when these disorders happen due to damage or disruptions in your brain or because of your genetics or inherited traits from your parents.

What can I expect if I have a circadian rhythm disorder?

If you have a circadian rhythm disorder, what you can expect varies depending on the specific disorder. In general, these conditions interfere with sleep when you try to do so and cause you to feel sleepy when you should be awake and alert. You may be able to manage or minimize these symptoms with changes to your sleep behaviors and treatment.

Circadian rhythm disorders aren’t dangerous directly, but they can increase the risk of dangerous situations. Falling asleep while driving or operating heavy machinery can be extremely dangerous. And even when a circadian rhythm disorder doesn’t put you in danger, it can still interfere with your life. That can make for problems at work, with family or loved ones, or during social events and activities.

How long do circadian rhythm disorders last?

How long circadian rhythm disorders last depends on many factors, especially the specific disorder you have, how well you manage the symptoms with sleep hygiene and other changes, and how well you respond to treatment. Sometimes, circadian rhythm disorders are permanent. This is especially true with disorders due to brain damage from degenerative brain diseases. Your healthcare provider can tell you more about what you should expect in your particular case.

Some circadian rhythm disorders reverse themselves naturally. An example of this is jet lag, which can last between two days and two weeks (the greater the time difference, the longer the symptoms last). Another example is shift work sleep disorder, which can resolve with a consistent night shift schedule or moving to a daytime shift.

How do I take care of myself?

If you suspect you have a circadian rhythm disorder, it’s a good idea to talk to a healthcare provider like a sleep medicine specialist or a behavioral sleep medicine psychologist. Doing so sooner rather than later can help you avoid more serious issues, such as daytime sleepiness-related accidents or problems at work or school.

Once you talk to a provider and get a diagnosis, it’s important to follow your healthcare provider’s guidance. That’s especially the case when it comes to adjusting your sleep-related habits, behaviors and routine. Sleep hygiene is often critical.

Other things that will help you manage a circadian rhythm disorder may vary depending on the disorder you have and your circumstances. Your healthcare provider is the best source of information on what you can do to improve your symptoms and avoid other issues.

What questions should I ask my doctor?

Some questions you may want to ask your provider include:

• What circadian rhythm disorder do I have?
• Does my circadian rhythm disorder have an identifiable cause?
• How is it affecting my sleep-wake patterns?
• What are the treatment options?
• How long does this disorder usually last?
• What can I do to manage this disorder?
• What should I avoid or not do if I have this disorder?