Circadian Rhythm Sleep Disorders: When Your Body Clock Is Off

Circadian rhythm sleep disorders happen when your body clock is out of step with the schedule you need to keep. The sleep itself is often normal, but it comes at the wrong time, so you can't fall asleep when you need to, or you can't stay awake. Treatment focuses on moving the clock with well-timed light, timed melatonin and a steady routine.

How your body clock works

Your brain has a master clock that runs on a cycle of about one day. It controls when you feel sleepy and alert, and when your body releases the sleep hormone melatonin. Light is the strongest signal that sets this clock. Morning light tends to shift it earlier, and evening light, including light from screens, tends to shift it later.

When the clock and your schedule don't match, you may have trouble sleeping at night, feel sleepy during the day, or both.

Delayed sleep-wake phase: why many teens run late

In delayed sleep-wake phase disorder (DSWPD), the body clock runs much later than usual. People can't fall asleep until very late at night and find it very hard to wake in the morning. On free days, they sleep late and feel fine.

This pattern often starts in the teen years. During puberty, the body clock naturally shifts later, and melatonin is released later at night.^[1] Late-night screens, homework and early school start times can make it worse. The American Academy of Pediatrics (AAP) urges middle and high schools to start no earlier than 8:30 a.m. so teens can get 8.5 to 9.5 hours of sleep.^[2]

A teen who can't fall asleep until late, struggles to get up for school and sleeps in on weekends is not simply lazy. If the pattern is strong and affects school or mood, it is worth an evaluation. Our pediatric sleep medicine page explains how we care for children and teens.

Other types of circadian rhythm disorders

• Advanced sleep-wake phase — the clock runs early. People get sleepy in the early evening and wake very early. It is more common in older adults and can run in families.
• Shift work disorder — working nights, early mornings or rotating shifts leads to insomnia, sleepiness or both.^[3]
• Jet lag — after flying across time zones, the body clock is still on the old time. It usually improves as the clock adjusts, and flying east is often harder than flying west.^[3]
• Non-24-hour sleep-wake rhythm — the clock is not set by daylight, so sleep times drift later day by day. It is most common in people who are totally blind.
• Irregular sleep-wake rhythm — sleep is broken into short pieces across the day and night with no main sleep period. It is seen most often in people with dementia and in some children with developmental or neurologic conditions.

How it is diagnosed

Diagnosis is mostly about the pattern of your sleep over time. A sleep specialist will ask about your schedule and may use:

• Sleep diary — you write down when you go to bed, fall asleep, wake up and nap, on both work or school days and free days.
• Actigraphy — a small wrist device that tracks rest and activity for several days to a few weeks. The American Academy of Sleep Medicine (AASM) suggests actigraphy for checking circadian rhythm disorders in adults and children.^[4] Learn more in what is actigraphy sleep testing.
• Questions about other causes — insomnia, sleep apnea, depression, medicines and caffeine can look similar. An overnight sleep study is used only when another sleep disorder is suspected.

Treatment: timed light, timed melatonin and routine

The AASM reviewed the research on body clock disorders in 2015. Much of the evidence was limited, so most of its recommendations are "weak" (conditional) ones. Your doctor will fit them to you.^[5]

• Timed light — bright light at the right time can move the clock. The guideline suggests morning light, with behavior changes, for children and teens with delayed phase, evening light for adults with advanced phase, and light for older adults with dementia who have an irregular rhythm. For adults with delayed phase, there was not enough evidence for a formal recommendation, though doctors often still use light.
• Timed melatonin — the guideline suggests melatonin taken at a set time for delayed phase in adults and children, for non-24 in blind adults and for irregular rhythm in children with neurologic conditions. It suggests against melatonin for older adults with dementia.
• A steady schedule — the same wake time every day, including weekends, plus dim light and fewer screens before bed.
• Care with sleeping pills — the guideline recommends against sleep-promoting medicines for older adults with dementia who have an irregular rhythm.

With melatonin, timing matters more than the amount. A low dose, timed by a doctor, is the usual approach; taken at the wrong time, it can shift the clock the wrong way. Melatonin is sold as a dietary supplement, so the amount in a product can differ from the label. Talk with your child's doctor before giving it to a child or teen. For shift work and jet lag, a plan may combine timed light, light blocking, planned naps and sometimes melatonin or other medicines.^[3]

When to see a sleep specialist

• Your teen can't fall asleep until very late — and is missing school, falling behind or very hard to wake.
• Your sleep times keep drifting — or you can't keep a regular schedule no matter what you try.
• You are sleepy at work or while driving — especially after night or rotating shifts.
• Melatonin or a new routine has not helped — or you are unsure about timing.

Trouble falling asleep can also have other causes; see what causes insomnia and when to see a sleep specialist.

Body clock care in Cedar Park

Dr. Minal Patel is board-certified in pediatrics and sleep medicine, so she sees both children and adults with sleep problems. Our practice treats insomnia, offers pediatric sleep medicine and provides in-lab and home sleep studies when another sleep disorder needs to be ruled out. We are accepting new patients. Office hours are Monday through Friday, 8:30 to 5:00. We accept Medicaid and CHIP for sleep patients. We do not take walk-ins.