Delayed Sleep Phase Syndrome (DSPS) is a disorder where you find it harder to go to sleep until very late at night. This can be as late as 4AM. In the morning, you will want to sleep in for longer, perhaps until the early afternoon. If you have to wake up earlier than this, then you will feel groggy, but as the day goes on, you will get more energy. Even if you wake up early, in the evening your body will still only want to go to sleep late at night. On the weekend, many people with DSPS will sleep in even later in the afternoon.
What causes DSPS? Your body contains a kind of internal clock that tells you when to wake up and when to go to bed. Scientists think that if you have DSPS, this clock is not running properly. A hormone called melatonin might be involved here. Your lifestyle can also be involved. Young adults often don’t feel very sleepy at night, so they stay up too late, and this moves the timing of their body clock.
DSPS is most common in teenagers. About 7% of teenagers have it. It can occur at other ages, but it is less likely.
For some people DSPS will go away by itself. If not, then you can see a sleep specialist. The specialist will suggest changes in your sleep routine to regularise the hours of sleep. He or she might suggest bright light therapy – either from morning sunlight or from a light box that is designed for the purpose. This is normally done for about an hour after you wake up. The specialist might also suggest that you take melatonin just before your bedtime. A further treatment for DSPS is called chronotherapy.
Once you are at the right bedtime and wake-up time it is very important that you keep the time of getting up as constant as possible. This includes week days and weekends. It is also important that you get plenty of good light in the mornings. This will lower your melatonin levels. Open your curtains and have your breakfast next to a brightly lit window. Stop using your computer any closer than an hour before your planned bedtime.
Advanced Sleep Phase Disorder or ASPD is a sleep disorder where you keep going to bed and waking up too early. For example, you might find it hard to stay up until a normal bed time such as 10pm. You might feel a strong urge to go to bed as early as 8-9pm. Once in bed you fall asleep quickly and sleep well for a few hours. However, you then wake up very early (e.g. 3-4 am) and find it very hard to go back to sleep. You often feel you don't get enough sleep, due to waking up so early in the morning. Importantly, if you went to bed even earlier (e.g. 6-7pm), you would be able to go to sleep then. But you would probably wake up even earlier after a few nights of this early-to-bed pattern.
A vital part of what makes us feel sleepy is our 24 hour body clock. This is located deep inside our brain, behind the eyes. It controls when we feel sleepy and alert. For most adults their body clock makes them feel sleepy between the hours of 11pm to 7am and alert at other times, including the early evening (6-9 pm) and morning hours (8-11 am). Those with ASPD have an early timed body clock that shifts those alert and sleepy zones to earlier clock times. This makes them feel very sleepy in the early evening and alert as early as 3-4 am. How the ASPD body clock timing shifts in this way is not well understood. It may be due to a shorter than normal cycle length, tending to complete the sleep-wake cycle in less than 24 hours.
ASPD is more common as we become older. Roughly 1% of middle aged to older people experience ASPD.
Based on the knowledge that ASPD relates to an early timed body clock, the aim of treatment is to change the body clock to a more normal timing. Two treatments can re-time the body clock: getting bright light visual stimulation and taking melatonin. The timing of when you have these is vital. Bright light visual stimulation should occur in the evening before you go to bed. The light should be brighter than normal indoor lighting. You can obtain it from specialized light boxes, or portable devices that you can wear, e.g. eye glasses. You may need an hour or two of bright light therapy before bed. Some will benefit from nightly use for a week. Others will need longer, sometimes several weeks, to get maximum benefit. It is best used late in the evening, perhaps turning the bright light device off half an hour before bed. To change your hours of sleep, you should gradually delay your bed time (e.g. 20 minutes later each night) until you get it to the time that you want. As you delay your bedtime, you will also be delaying the time of your bright light exposure and melatonin intake.
As you can see, this treatment is quite complex. You may want to consult a sleep specialist, especially if you don’t have success treating ASPD by yourself.