Within the hypothalamus of the brain a circadian rhythm (or “body clock”) controls the timing of sleep and wakefulness. It works by synchronizing sleep (and other biological processes) with the light/dark cycle. Circadian rhythm disorders occur when a person gets the correct quantity and quality of sleep but at undesired times i.e. their “body clock” is out of sync. One example of a circadian rhythm disorder is Advanced Sleep Phase Disorder (ASPD), which is characterized by early evening bedtimes (approximately 8-9pm) and early morning awakenings (approximately 4-5am). It contrasts with Delayed Sleep Phase Disorder (DSPS) which is associated with late bedtimes (between 1-6am) and late awakenings (between 10-2am). The estimated prevalence of ASPD is 1% and it is most commonly seen in older adults. Individuals suffering from ASPD can often feel isolated because their overwhelming drive to sleep can render them unable to participate in occupational, family or social activities in the evening hours.

The exact cause of ASPD is not completely understood. However, there appears to be a strong genetic link, with sufferers having a 50% chance of passing it onto their children. Whether a sufferer needs medical treatment depends on their personal circumstances. The disorder itself is not necessarily dangerous or unhealthy. Some sufferers are able to achieve the correct amount of sleep if their family and work routines allow them to go to bed early and wake early. However, with some sufferers, their family and work routines render it impossible to go to bed early and as a result they experience sleep deprivation. If ASPD is causing sleep deprivation then you should consult your doctor because it can have a negative impact on both physical and mental health.

If you decide to opt for treatment, you may need to undergo polysomnography; a sleep test which records heart rate, breathing rate, brain activity as well as eye and leg movements. This will allow doctors to monitor your sleep/wake cycle and it can also be used to evaluate whether another sleep disorder may account for your symptoms. Other strategies include maintaining a sleep diary to monitor sleep/wakefulness patterns. Doctors may provide behavioral counseling in order improve the quality of your sleep and maximize your output during waking hours. One treatment approach is chronotherapy, which involves gradually delaying your bed time over small increments each day (e.g. 20 min) until your sleep timing eventually meets your desired schedule. Another option is bright light therapy. Exposure to bright light in the early evening can emulate sunlight which may stave off sleep and reset your circadian rhythm system. If you are thinking about making a permanent change to your sleep pattern then you should consult a doctor or sleep specialist.


Committee on Sleep Medicine and Research, Board on Health Sciences Policy, Institute of Medicine    (2006). Sleep Disorders & Sleep Deprivation: An Unmet Public Health Problem, National        Academies Press.

PAINE, S. J., FINK, J., GANDER, P. H. & WARMAN, G. R. 2014. Identifying advanced and delayed   sleep phase disorders in the general population: a national survey of New Zealand adults.        Chronobiol Int, 31, 627-36.

Reviewed by Dr. Emma Mitchell, PhD____________________________

Older content:

Advanced Sleep Phase Disorder (ASPD) is a circadian rhythm disorder causing people afflicted with it to have a natural tendency to go to sleep and wake up at times considered early than what is normal. It is one of numerous circadian rhythm sleep disorders, and is the opposite of a delayed sleep phase, in which people go to bed and wake up at times considered later than what is normal.

People with advanced sleep phase routinely go to sleep in the early evening, between 6 and 9 pm, and wake up in the early morning, ranging from 1 to 5 am. Having advanced sleep phase is not necessarily a precursor to having or being at a risk of acquiring other sleeping disorders. Many people who have ASPD get quality sleep on a par with people sleeping at more normal times.

Circadian rhythm disorders may happen due to poor sleep hygiene or stress related factors though, and this could lead to the development of other sleep related disorders.
All human functions influenced by the circadian rhythm are also affected and moved forward as a result of the advanced sleep phase, including an earlier release of melatonin and other hormones, an earlier body temperature curve, and natural tendencies to eat meals earlier than usual.
Many people are able to fully function in society with advanced sleep phase disorder, but others may feel alienated when forced to skip out on social gatherings that occur in the evenings, or attend them with limited faculties due to overwhelming sleepiness. This could lead to further stress and the development of additional sleeping disorders. Sleep deprivation could also be the result of too many forced late evenings, as the individual will still wake up at the regular early time in most cases, no matter the amount of sleep attained.
People with advanced sleep phase disorder may attempt to self diagnose and cure their condition by forcing late evenings, and then remaining in bed as long as possible in the mornings or taking sleeping medications to get lengthy sleep and attempt to alter their circadian rhythm. These tactics are unlikely to succeed, and may lead to other sleeping or non sleeping related issues. Those wishing to institute a permanent change to their circadian rhythm should consult a doctor or sleep specialist.
Advanced sleep phase disorder is uncommon, affecting only 1% of adults, and has higher rates of occurrence in seniors. This is in contrast to delayed sleep phase, which occurs in as many as 15% of adults, and has a higher rate of occurrence in younger adults. Advanced sleep phase affects both genders equally, and has a strong genetic link. Studies on familial advanced sleep phase have shown that as many as 40 to 50% of people with a familial link to the disorder will themselves have it.

Advanced sleep phase can also be caused, sustained or increased by environmental or social factors. This largely explains the much higher rate of delayed sleep phase disorder as opposed to advanced sleep phase disorder, especially in younger adults who are socially active.

Depending on the personal situation, you may or may not need to seek treatment for advanced sleep disorder. The disorder itself is not necessarily dangerous or unhealthy, and treatment need only be sought if it is having a large effect on your social or business life that it is causing problems in those areas, or stress that may lead to other problems.
If you would like more information about this, or if you are interested in making a change, you should consult your doctor. The doctor will look at your individual case and make recommendations about what should be done. If the advanced sleep phase is not causing overt problems in your life, the doctor may advise you to not make any changes, as taking the step to upset your circadian rhythm could lead to other problems.
If you opt for treatment, you may need to undergo polysomnography – an overnight sleep study. This will give the doctors more data concerning the times you are sleeping and waking, the quality of sleep you are getting, and that no other sleeping related disorders are present. In lieu of this, the doctor may be content with keeping a sleep diary, which tracks subjectively the times you go to sleep and wake up; an attempted judgement by you of the quality of sleep you achieved and how long it took you to fall asleep.
If you are content to maintain your advanced sleep phase, your doctor or sleep specialist can help you with educational and behavioral counseling to maximize your output during waking hours, and limit things you may inadvertently do to harm your sleep.

If seeking a treatment for advanced sleep phase, you will be set on a course that slowly increases your in-bed and waking times. This is a long process, with very small increments each day. You may also try bright light therapy, which emulates sunlight in the early evening to ‘trick’ the body into staying awake


Reviewed September, 2007


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