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.
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
Reviewed September, 2007