Delayed sleep-wake phase syndrome, or delayed sleep-wake phase disorder (DSPD), is characterized by the inability to fall asleep, difficulty waking up on time, and, in some cases, daytime sleepiness or depression. If you have delayed sleep-wake syndrome, you fall asleep and wake up later despite a regular sleep schedule. These symptoms may cause difficulties in school or work. DSPD most commonly occurs in adolescent men and middle-aged women.
DSPD is one of many circadian rhythm sleep disorders (CRSDs). The circadian rhythm is a 24-hour cycle run by your biological clock that controls essential body functions like temperature, hunger, digestion, the release of hormones, and when you fall asleep and wake up. Light and darkness influence your circadian rhythm, so it can be affected by late-night light from electronics, as well as jet lag from traveling across time zones.
There are two types of DSPD. These are characterized by the onset of melatonin, the sleep hormone:
The most common sign of delayed sleep-wake phase syndrome is being unable to fall asleep at a socially normal bedtime. This late bedtime makes waking up early difficult, and the lack of a full night of sleep can trigger many symptoms:
These symptoms may worsen if you frequently change your sleep schedule, such as traveling across time zones.
Common causes of circadian rhythm sleep disorders include:
However, the exact cause of delayed sleep-wake phase syndrome is still unclear. Some experts hypothesize that people with DSPD have longer circadian periods than average. A longer circadian period means that you won’t have the same biological drive to fall asleep at the same time as the average person. Alternatively, people with DSPD struggle to advance normally through the day because they miss a key window of alertness when waking later. Other theories suggest sensitivity to light at night or irregularities in the sleep regulatory system.
Delayed sleep-wake phase syndrome is more prevalent in young men and middle-aged women. Overall, however, there is no significant difference in DSPD among genders. The disorder is also quite prevalent among adolescents and teenagers. The circadian rhythm changes during the teenage years, causing delays in the sleep-wake phase. The onset of melatonin, the sleep hormone, begins about an hour later in teens than adults. As a result, DSPD affects anywhere between 7% and 16% of adolescents. One study found that 90% of adults with DSPD experience onset of symptoms in childhood or adolescence.
Depression is common in people diagnosed with DSPD. Up to 64% of people with DSPD also have depression. New research also suggests a link between delayed sleep phase syndrome and ADHD. As many as 75% of adults diagnosed with ADHD in childhood also have circadian rhythm delays.
Keeping a sleep diary is helpful in determining whether or not you may have delayed sleep-wake phase syndrome. In the sleep diary, you note when you go to bed, when you fall asleep, and when you wake. This log helps your healthcare provider get a full picture of your sleep habits.
Your healthcare provider may also recommend an actigraphy. You wear the actigraph on your wrist like a watch, and the device records movement and light to determine when you are asleep or awake.
A sleep study, also called polysomnography, can also be used to diagnose DSPD. You may have to take the sleep study twice. On one test, you sleep to model a “weekday” schedule and on the other, you model a “weekend” sleep schedule. However, these tests may be cost-prohibitive.
The goal of delayed sleep-wake phase disorder treatment is to align your circadian rhythm to meet target sleep and wake times. Treatment typically begins with improving sleep hygiene, and you may need to reset your sleep routine. Qualities of good sleep hygiene include:
The elimination of blue light devices before bedtime is key in improving DSPD symptoms. The blue light can suppress the sleep hormone melatonin and therefore disrupt your sleep cycle.
In addition to improving sleep hygiene, bright light therapy is a viable treatment option. Research shows that bright light exposure in the first one or two hours of the morning advances your circadian rhythm. With your circadian rhythm advanced, you should fall asleep earlier and wake up earlier.
You might also consider a melatonin supplement in the hours before your bedtime. At this time, a consensus on exact timing and dosage of melatonin has not been established. Consult your doctor to determine how much to take and when to take it.
If you think you have delayed sleep-wake phase syndrome, talk to your healthcare provider about your symptoms. They can diagnose the disorder and help you determine an appropriate treatment plan. With consistent attention to sleep hygiene and use of other treatments, you can manage the effects of DSPD and even alter your sleep and wake times.