What is delayed sleep-wake phase disorder?

Delayed sleep-wake phase disorder (DSP) is a circadian rhythm disorder. It consists of a typical sleep pattern that is “delayed” by two or more hours from societal norms. This delay occurs when your internal sleep clock (circadian rhythm) is shifted later at night and later in the morning. Once sleep occurs, the sleep is generally normal. But the delay leads to a pattern of sleep that is later than what is desired or considered socially acceptable. This pattern can be a problem when it interferes with work or social demands.

If you have DSP, you are likely to prefer late bedtimes and late wake-up times. When left to your own schedule, you are likely to have a normal amount and quality of sleep. It simply occurs at a later time.

One sign of DSP is difficulty falling asleep until late at night. Another sign is having a hard time getting out of bed in the morning for work or school. These signs can make DSP look like insomnia. Also, like insomnia, DSP can impair your alertness and performance during the day. It can lead to excessive sleepiness and fatigue.

What are symptoms of delayed sleep-wake phase disorder?

Symptoms of DSP include:

A delayed sleep pattern in relation to desired sleep and wake times
Trouble falling asleep at the desired bedtime
Inability to wake up in the morning
Normal duration and quality of sleep when there is no need to go to sleep or wake up at a specific time
A stable but delayed sleep pattern for at least seven days

It is also important to know if there is something else causing your sleep problems. Some common examples are:

Another sleep disorder
A medical condition
Medication use
A mental health disorder
Substance abuse

What are risk factors for delayed sleep-wake phase disorder?

The exact rate of DSP is unknown in the general population. It is much more common in teens and young adults. About 7% to 16% of teens and young adults may have DSP. DSP is likely to be found in 10% of people with a complaint of insomnia. People who tend to be “evening types” or “night owls” are likely to develop DSP.

A family history of DSP is common in about 40% of people with the disorder and there is likely a genetic component. Some environmental factors may also be involved. Both a lack of exposure to morning sunlight and too much exposure to bright light in the evening may increase symptoms of DSP.

How to diagnose delayed sleep-wake phase disorder?

It is easy to confuse DSP with normal variations of sleep and other types of insomnia. Consulting with a sleep doctor is your best bet to help clarify current sleep problems. Your doctor will also be able to help you develop a plan to correct these problems.

Your doctor will do a thorough physical exam. She will also discuss the history of these sleep problems. It would be helpful to keep a sleep diary prior to seeing a sleep doctor. Bring this information with you to the appointment. A sleep diary is a way to track your sleep pattern. You record the time you get into bed, the time required to fall asleep, and the time you wake up in the morning. If you have DSP, your sleep diary will likely show a regular pattern of difficulty falling to sleep, few or no awakenings once asleep, and a sleep duration that is reduced during the work week and lengthy on the weekend.

A sleep study, while not normally needed for someone who has DSP, may be required. Your doctor will determine if a sleep study is needed. This study is called polysomnography. It records your brain waves, heartrate, and breathing as you sleep. It also monitors how your arms and legs move. This study will help determine if there are any objective sleep disorders related to your sleep problem.

How to treat delayed sleep-wake phase disorder?

Strategically timed low dose melatonin use has been shown to be an effective treatment option in teens, and it may be somewhat effective in adults. Melatonin is a hormone that is widely available in supplement form. The hormone is naturally produced by your body and plays an important role in sleep. It helps regulate your sleep-wake cycle by signaling to your body when the time for sleep is approaching.

Melatonin dosage and timing should be discussed with a sleep doctor to ensure the most effective treatment strategy.

Bright light therapy is another proven technique for changing your internal circadian rhythms, but its specific use for DSP has not been well validated. In theory, exposure to bright light should occur shortly after waking up at the desired time in the morning. Then bright light in the evening hours should be avoided. Light therapy combined with behavioral therapy for children and adolescents may be a treatment option.

Cognitive behavioral therapy helps you change actions or thoughts that keep you awake. It helps you develop habits that promote a healthy pattern of sleep.