What Are Circadian Rhythm Disorders?
Circadian rhythm disorders are problems with your circadian rhythm, the "internal body clock" that keeps your biological processes in step. Your normal circadian rhythm is set by the cycle of light and dark over 24 hours. It plays a key role in things like when you sleep and when you wake. Patterns of brain waves, hormone production, cell regrowth, and other activities are linked to this cycle.
People with circadian rhythm disorders may have problems:
- Falling asleep
- Staying asleep
- Waking up too early and not being able to go back to sleep
- Getting sleep but not feeling refreshed by it
- Feeling alert during the day
Other symptoms may include:
Circadian Rhythm Disorder Causes
Things that can cause circadian rhythm disorders include:
Common Circadian Rhythm Disorders
- Jet lag, or rapid time zone change syndrome. This involves symptoms like too much sleepiness and a lack of daytime alertness in people who travel across time zones. It gets worse with each time zone crossed, especially when traveling east.
- Shift work sleep disorder. This sleep disorder affects people who often rotate shifts or work at night. A conflict between someone’s circadian rhythm and the time of their shift can mean they get up to 4 hours less sleep than the average person.
- Delayed sleep phase syndrome (DSPS). This is a disorder of sleep timing. People with DSPS tend to fall asleep very late at night and have a hard time waking up in time for work, school, or social events. It’s especially common in teens and young adults.
- Advanced sleep phase syndrome (ASPS). This is a disorder in which a person goes to sleep earlier and wakes earlier than they wanted. For example, they might fall asleep between 6 and 9 p.m. and wake up between 1 and 5 a.m.
- Non-24-hour sleep-wake disorder. This disorder often affects people who are blind because the circadian clock is set by the light-dark cycle. With this condition, that cycle is disturbed. It can cause a serious lack of sleep time and quality at night and sleepiness during daylight hours.
- Irregular sleep-wake rhythm disorder. With this disorder, people’s circadian rhythms are jumbled. They may sleep in a series of naps over 24 hours.
Circadian Rhythm Disorder Diagnosis
Talk to your doctor if:
- You sleep poorly for more than 1 month and notice trouble concentrating, forgetfulness, less motivation, or severe daytime sleepiness
- You have trouble falling asleep
- You awaken in the morning feeling tired and unrefreshed
Your doctor will begin by asking about your symptoms, taking a medical history, and doing a physical exam.
They may also use:
- Sleep logs. A sleep log identifies the sleep-wake cycles in your regular environment (when at home and not traveling or working odd hours). You’ll be asked to write down when and how well you sleep over a period of time.
- Sleep studies. Usually done in a sleep lab, sleep studies monitor you during sleep, measuring levels of oxygen, number of times you stop breathing, and how much you snore.
- Imaging studies, such as CT scan and MRI, can check for neurological diseases, sinus infections, or blocked airways.
- Epworth Sleepiness Scale. This questionnaire rates responses to eight situations, on a scale of 0-3, of their associations with sleepiness.
- Actigraphy. You’ll wear a motion sensor on your nondominant wrist for a week to measure sleep-wake cycles.
Circadian Rhythm Disorder Treatments
Your treatment will depend on your condition. The goal is to fit your sleep pattern into a schedule that matches up with your lifestyle. Treatments may include:
- Bright light therapy. You reset your rhythm by being around a bright light for a certain time each day.
- Sleep hygiene. You learn how to improve your circadian rhythm with changes to your bedtime routine or sleep environment.
- Chronotherapy. You slowly adjust your bedtime until it reaches the time you want.
- Lifestyle changes. Things like scheduling naps, being careful about your exposure to light, and avoiding caffeine or nicotine for some time before bed can help.
Medications to treat circadian rhythm disorders include:
This natural hormone is made by a gland in the brain at night (when it’s dark out). Melatonin levels in the body are low during daylight hours and high during the night.
Melatonin supplements, available over-the-counter, may be useful in treating jet lag and sleep-onset insomnia in elderly people with melatonin deficiency. But they haven’t been approved by the FDA, so it isn’t clear how much melatonin is safe and effective.
Melatonin receptor stimulant
Rozerem, a melatonin receptor stimulant, needs a doctor's prescription. It’s approved by the FDA for treating insomnia marked by trouble falling asleep.
Short-acting benzodiazepines, such as Xanax, are often prescribed in the early treatment of a circadian rhythm disorder and are used in conjunction with behavioral therapy. Long-term use isn’t recommended because of potential side effects, such as the rebound phenomenon (the original problem returns at a higher level), and the risk of dependence.
These prescription sleep medications, such as Ambien, Sonata, and Lunesta, aren’t associated with the rebound phenomenon seen with benzodiazepines. But the FDA has warned that “rare but serious injuries” have happened in people taking them, resulting from "complex sleep behaviors'' such as sleepwalking and sleep driving.
Orexin receptor antagonists
Orexins are chemicals involved in regulating the sleep-wake cycle, helping keep you awake. This type of drug changes the action of orexin in the brain. The only approved drug in this class is Belsomra.
If you have circadian rhythm disorder because of shift work, your doctor may prescribe this stimulant. You take it an hour before the start of the work shift to feel more awake.