Circadian Rhythm Disorders Causes and Risk Factors

---

Circadian rhythm disorders occur when your sleep-wake cycle is out of sync with your environment. Many factors, both internal and external, can cause you to have problems sleeping and raise your risk for a circadian rhythm disorder.

Genetic conditions that affect your brain or hormones can cause circadian rhythm disorders. For example, Smith-Magenis syndrome is a genetic condition that may affect how much or how often your body makes the hormone melatonin , which helps you sleep. Sleep patterns may be completely reversed, causing daytime sleepiness and wakeful nights.

Did you know that your sleep-wake cycle and your risk for circadian rhythm disorders may be different from someone else’s? This is controlled by your genes in your DNA. Some people naturally wake early, while others naturally stay up late. Some people can more easily adjust their circadian rhythm to match their environment. If you are one of these people, you may be less likely to develop jet lag disorder and shift work disorder. You may develop circadian rhythm disorders if your patterns do not align with your work, school, or social responsibilities. Talk to your doctor about your symptoms.

Many things can lead to a circadian rhythm disorder. Some you cannot change, like your age, family history, or sex. Some you can manage, like your lifestyle or occupation.

Age

The rhythm and timing of your sleep-wake cycle can change with age because of changes in your brain. Teens may naturally have a later bedtime than adults, which raises their risk for delayed sleep-wake phase disorder. Older adults usually go to sleep and wake up early. This raises their risk for advanced sleep-wake phase disorder. Older adults are also at higher risk for shift work disorder and jet lag disorder.

Environment or occupation

People who work during the night have a higher risk for shift work disorder. Jet lag disorder is more common in pilots, flight attendants, athletes, and people who travel often for business.

Family history or genetics

Your genetic preference of an early or late bedtime can raise your risk for advanced or delayed sleep-wake phase disorder if your rhythm is out of sync with your environment or social responsibilities. Changes in the genes that control your circadian rhythm, called circadian clock genes, can also raise your risk.

Lifestyle habits

Lifestyle habits can raise your risk for circadian rhythm disorders. These include:

• Alcohol use
• Chronic caffeine use
• Frequent air travel
• Illegal drug use
• Lack of exposure to natural light during the day
• Unhealthy sleep habits, such as regularly staying up late and being exposed at nighttime to artificial light, such as from a TV screen, smartphone, or very bright alarm clock

Other medical conditions

Several medical conditions can increase your risk for circadian rhythm disorders, including:

• Autism spectrum disorders
• Certain genetic conditions, such as Smith-Magenis syndrome, Angelman syndrome, and Huntington’s disease
• Conditions that affect eyesight, such as blindness and macular degeneration, which raise the risk for non-24-hour sleep-wake rhythm disorder
• Conditions that cause damage to the brain, such as traumatic brain injuries, strokes, and brain  tumors
• Mental health conditions, such as bipolar disorder, major depression, obsessive-compulsive disorder, and schizophrenia, which raise the risk of delayed sleep-wake phase disorder
• Neurodegenerative diseases, such as Alzheimer’s disease, dementia, and Parkinson’s disease: These conditions are more common in older adults and can increase the risk for irregular sleep-wake phase disorder.

Sex

Men are more likely to have advanced sleep-wake phase disorder than women.

Women may be more likely to experience circadian rhythm disorders at certain stages of life.

• Hormonal changes that happen during pregnancy, after childbirth, and at menopause can cause problems with sleep.
• Discomfort during pregnancy may also prevent good-quality sleep.
• After childbirth, sleep interruptions and nighttime exposure to light while caring for a newborn can increase your risk for circadian rhythm disorders.

If you are at risk for circadian rhythm disorders, your doctor may recommend certain lifestyle changes to help prevent a circadian rhythm disorder. For example, your doctor may talk to you about avoiding bright light and caffeine close to your bedtime.

Other preventive steps may help depending on your stage of life or work.

For new parents

While caring for a newborn at night, keep the lights as dim as possible.

For shift workers

The following steps may help prevent shift work disorder:

• Take a short nap before your night shift to help prevent sleepiness at work.
• Adopt a sleep schedule on your days off that overlaps with your sleep time on workdays.
• Avoid multiple schedule switches between day and night shifts, if possible.

For long-distance travel

The following steps may help prevent jet lag disorder:

• A few days before traveling, begin adjusting your sleep-wake cycle to match the time at your destination. You may gradually change your sleep schedule and use bright light to help advance or delay your waking time.
• If you can, arrive at your destination a few days before an important event, to help you gradually adjust to the local time. Your body adjusts to adjusts to 1 to 1.5 changes in time zones per day.
• Spend plenty of time outside at your destination. Outdoor light may shorten symptoms of jet lag.