also Delayed Sleep Phase Disorder (DSPD), Delayed Sleep-Wake Phase Disorder (DSWPD)
Delayed Sleep-Phase Syndrome (DSPS) is a circadian rhythm sleep disorder in which the individual's internal body clock is delayed with respect to the typical sleep at night, rise in the morning pattern of most adults. Such people are sometimes called "night owls", though for those with DSPS, their hours are not by choice.
People with DSPS generally fall asleep late at night, often in the pre-dawn hours, and wake in the late morning or in the afternoon. Furthermore, there is a striking inability to fall asleep at an earlier, more typical bedtime. As a result, many people with DSPS have been labelled as insomniacs. But if such a person is allowed to follow his internal sleep pattern, he generally has no problems with either falling asleep or waking naturally.
However, if he ignores his internal clock and attempts to live on a normal schedule, DSPS can cause difficulty thinking clearly, driving safely, and generally functioning well. Over time, this may significantly reduce a person's productivity and enjoyment of life, and can lead to clinical depression or other stress-related medical problems.
These are much the same problems that would be expected if an adult with a normal sleep pattern forced himself to go to sleep in the late afternoon and to wake up in the middle of the night. Although some people are able to shift their schedules in this way, others find it difficult or impossible to do so and still function at an acceptable level.
This suggests that DSPS is a two-pronged issue: one is the body's daily cycle, which is later than normal. The other is the difficulty or even inability to shift one's schedule to a different time.
In an excellent review article, Circadian rhythm sleep disorders (CRSD) by Yaron Dagan, he says
CRSD [circadian rhythm sleep disorders] patients differ from night or morning type people … in the rigidity of their maladjusted biological clock. While “owls” and “larks” prefer morning or evening, they are flexible and can adjust to the demands of the environmental clock. CRSD patients, on the other hand, appear to be unable to change their clock by means of motivation or education.
DSPS patients are typically unable to fall asleep before 2 a.m., regardless of how early they got up the previous day or how tired they may be. For some, it is impossible to sleep before 6 or 7 a.m.
Some people with DSPS manage to function on a few hours' sleep a night during the working week, then "catch up" by sleeping excessively at the weekend. But their ability to think clearly often suffers, and the irregular sleep-wake pattern may well have long-term consequences.
Some DSPS people are on occasion able to rise early for a few days at a time. But typically they are not able to perform well on this schedule, and they would not be able to keep this up on a consistent basis over a longer period of time. Also, such a temporary change can "confuse" the body's circadian clock, resulting in an erratic sleep-wake cycle and making it difficult to return to the previous regular schedule.
Many people with this disorder deny the existence of a problem and refuse to accept that they may not be suited to working a 9-to-5 job. This denial often is encouraged by friends and relatives claiming there is no such problem as DSPS and accusing the DSPS individual of "just being lazy" or lacking will power.
Many others are not even aware that such a syndrome exists, and experience life as a constant struggle to get up on time, to stay awake, and to perform the activities required by their job or their family. Such a person often fails courses in school or loses jobs. This can affect his confidence and self-worth, and can cause social problems and health issues.
Attempting to force oneself through a daily 9-to-5 schedule with DSPS has been likened to constantly living with 6 hours of jetlag. Someone said it was like trying to push a boulder uphill your entire life. It's a daily struggle which in the long run can lead to depression or physical illness.
DSPS was first formally described in 1981 by Dr. Elliot D. Weitzman and others at Montefiore Medical Center. It is responsible for 7–10% of patient complaints of chronic insomnia. However, as few doctors are aware of it, it often goes untreated or is treated inappropriately; DSPS is often misdiagnosed as primary insomnia or as a psychiatric condition.
For many others, the disorder develops during adolescence.
Some people with DSPS also have other sleep disorders which compound their problems. Some have sleep apnea, which interferes with getting good rest even during their natural sleep time. Others report restless leg syndrome or other causes of poor quality sleep. These people generally require more than eight hours of sleep a night to function well, in addition to needing a shifted schedule.
Even just monitoring one's temperature to the required accuracy must be done with care. One must not eat, drink, or exercise for half an hour before each measurement. One also needs a sufficiently accurate thermometer - most home digital thermometers are not any more accurate than about 0.5° F., despite having displays that can be read to greater apparent precision. And ear probes, which provide the quickest readings, are even less accurate.
But there is a bigger problem here. One's sleep cycle affects one's temperature rhythm, as does the times one eats and any activity. So if one is sleeping on a delayed schedule, is the measured temperature cycle simply the result of that sleep schedule? Or is the temperature cycle the result of the underlying body clock cycle? In order to untangle this, researchers put subjects into a "constant routine" in which they are forced to stay awake for at least 24 hours, in a recumbent position without any physical activity, and with small amounts of food intake every hour. This is an unpleasant procedure, and expensive to administer, and isn't routinely done for patients. It is done in research studies.
Recent research on the eye has found three kinds of receptors, rather than the two kinds (rods and cones) previously known. This third type of receptor (called "intrinsically photosensitive retinal ganglion cells", abbreviated as "ipRGC") is sensitive to light, and helps entrain an organism's circadian rhythm to daylight. Some blind people, without any perceptual vision, nevertheless maintain a regular daily schedule, while others do not. It seems reasonable that the former group has functioning receptors of this third kind, while the latter group does not. Equally reasonable is the possibility that some normally sighted people are deficient in this third kind of receptor, and so do not entrain their schedules well to the usual daylight cycle.
A recent study by M Uchiyama et al (abstract) concluded:
These findings suggest that poor compensatory function for sleep loss predisposes DSPS patients to failure to reset their sleep phase. Our results provide implications for understanding not only the pathophysiology of DSPS but also the biological basis for why some people can change their sleep schedule easily according to personal or social demands while others cannot.
There is no permanent cure for Delayed Sleep-Phase Syndrome. The suggested treatments only provide ways to manage the condition. Often, several of these treatments are used together. They can be successful, at least partially, with some patients. But for others there is no improvement, and social and work patterns must either be adjusted to accommodate the delayed schedule of the patient, or physical and mental dysfunction as described above will result. Even when one's sleep time can be shifted, there is often an impact on mental functioning. As a fellow sufferer said to us: It's sad that even when circadian manipulation works, it really doesn't (at least, for some of us).
Avoid caffeine within six hours of bedtime. Also avoid alcohol: while alcohol may help one to fall asleep initially, it generally causes the restorative quality of sleep to suffer. Do not do any serious exercise for three hours before bedtime. And relax for a while before going to sleep.
You must go to bed at the same time every night, seven days a week, so that your body has a regular schedule to adapt to. And you should avoid naps late in the day, as that will make it more difficult to fall asleep at the appointed time.
Recommended exposure is 10,000 lux for ½ to 2 hours. The 10,000 lux is important. Lower intensity requires much longer exposure. Note that the intensity is a function of how far your eyes are from the light: sit twice as far away, and the intensity is typically only one quarter as much! The commercially available lights intended for this purpose are rated, for example "10,000 lux at 12 inches". Needless to say, the light must fall on your eyes, though you do not have to look directly into it.
The timing of the light exposure is critical. There is a point during the body's sleeping period, such that exposure before that time will delay the sleep cycle even further, but exposure after that time will advance it (move it earlier). The general rule is to sit in front of the light immediately on arising.
How effective is this treatment? Many have reported sufficient improvement that they are able to function reasonably well on a traditional 9-to-5 work schedule. Others find that after a while on a normal schedule they seem disconnected from the world, disoriented. Some find it helps partially, and are able to advance their schedule an hour or so. In addition, some people report side effects, such as feeling hyperactive after the light exposure. Shortening the exposure fixes that. Others report eye pain or puffiness, or headaches, including migraines. These people must move the therapy to a later time, where it may be less effective, or abandon it entirely.
While it takes a very bright light in the morning to move your sleep cycle earlier, even moderate light in the evening may move your schedule later. Blue or blue-green light (which are also present in white light) have an especially strong effect. Some DSPS people can fall asleep earlier if they restrict their exposure to light for several hours before bedtime by using only dim lights in their homes and avoiding TV, phone screens and comuter monitors during that time.
Another strategy is to filter out the blue components of the light by wearing blue-blocking glasses in the evening. Alternatively, computer screens can be covered with a colored gel that filters out blue light. Software such as f.lux reduces the blue from your computer monitor in the evening.
Melatonin has been recommended by doctors to assist in advancing (making earlier) people's sleep times. The usual timing is to take it from ½ to 2 hours before the desired sleep time. Recommended dose is typically between 1 and 10 mg, although some people appear to achieve useful effects with as little as 0.1 mg (100 micrograms). Both the timing and the dose need to be adjusted on an individual basis.
Recent reports suggest that to be most effective in advancing one's circadian rhythm one should take it much earlier, and in doses small enough not to feel tired right away. Six to eight hours before desired sleep time has been reported as optimal.
Many people report side effects from taking melatonin, especially with the larger doses. Some feel groggy and hung over the next day. Nightmares, vivid dreams and depression are often noted. A few report migraine attacks or other mood changes. In these cases, lowering the dose may minimize the side effect. A few people report increased restlessness and poor sleep. For them this therapy may have little value. Also, there is little data on long-term effects, including whether taking melatonin for years would make it difficult to fall asleep without it.
Melatonin is illegal in some countries. In some others it may be available only on a specialist's prescription. In the United States it is legal and available over the counter, but it is unregulated. Buy from a respected manufacturer to be sure you are getting what is on the label.
Note that while melatonin is believed to help in shifting one's circadian rhythms, this is not true of other sleeping pills. In addition, most other sleeping pills result in habituation, a lessened effect for the same dose, after taking them for a while.
The real difficulty comes with sticking to the new schedule. The patient must rigorously maintain the new schedule, seven days a week, for as long as he wants to be on it. Any delay in getting to bed, even for one night, is likely to allow his body clock to shift later, and make it difficult to impossible to shift earlier again. This then necessitates repeating the whole around-the-clock process again.
As a result, there are no late nights out with friends, no staying up with a sick child, no late nights trying to meet a school or work deadline. In practice, most people find such an exacting schedule impossible to adhere to in the long run, and so the chronotherapy ultimately fails.
Additionally, some DSPS people find that the early (for them) schedule feels unnatural and disorienting, and they cannot perform their best work following such a schedule.
There is also some data (e.g. this NEJM letter) indicating that the chronotherapy can lead to non-24-hour disorder, which may be even more difficult to deal with. In other words, where one has started with a delayed schedule which is the same every day, one may end up with a schedule that shifts later every day.
Another approach has also been reported, called "Sleep Deprivation Phase Advance". This involves staying up around the clock and then going to bed 90 minutes earlier than the patient's previous sleep time. Let the new time stabilize, and repeat. This is described in more detail in this Sleep Review article. The same difficulties maintaining the new schedule apply.
Much of the information on this web site is based on the experiences of participants in the niteowl listserv. This is a mailing list for people with DSPS to share their experiences. It's a good place for people just discovering this syndrome to hear how others deal with it. For further information, and to sign up, click on this link: http://circadiandisorders.org/list.
There is an organization called Circadian Sleep Disorders Network created to promote awareness of, and accommodation for, people with DSPS and other circadian sleep disorders. There is lots more information on their website, and we encourage you to join.
There are a number of other web pages out there about Delayed Sleep-Phase Syndrome. Most have been written by people who have never experienced it. Often, they strive to be optimistic about the available treatments. But while the treatments may be effective for some people, a large number of DSPS sufferers are not able to achieve and maintain a normal sleep-wake schedule.
Here are some links to other sites with related information:
Circadian Sleep Disorders Network
An ongoing blog about DSPS: delayed2sleep
Delayed Sleep Phase Syndrome by Su-Laine Yeo
Circadian Sleep Disorders Association FAQ
Delayed Sleep Phase Syndrome on healthcommunities.com
Delayed Sleep Phase Syndrome on sleepdisorders.about.com
Delayed Sleep Phase Syndrome on stanford.edu
DSM-IV Circadian Rhythm Sleep Disorder
The SunBox Co., one of many suppliers of therapeutic lights
Delayed Sleep Phase Syndrome on Health-cares.net
Sleep Disorder Info & Resources (not much on DSPS)
B-Society advocating for late risers
Excellent list of additional links
One person's experience with DSPS
Circadian rhythm sleep disorders (CRSD), an excellent review article by Yaron Dagan
A good article in the popular press
A great description of life with DSPS