Delayed sleep phase

Delayed sleep-phase syndrome (DSPS) is a chronic, fairly common, disorder of sleep timing. People with DSPS tend to fall asleep at very late times, and also have difficulty waking up in time for normal work, school, or social needs. DSPS is treatable, but cannot be cured. As few doctors are aware of its existence, it is often mistaken for other types of insomnia, and treated inappropriately.

It is estimated that 7% of adolescents have DSPS, and studies indicate that it is responsible for 7 -10% of cases of chronic insomnia..

Main symptoms

 * DSPS causes sleep-onset insomnia. Often, DSP individuals report that they cannot sleep until early morning. Unlike most other insomniacs, however, they fall asleep at about the same time every night, no matter what time they go to bed.
 * Unless they have another untreated sleep disorder such as sleep apnea in addition to DSPS, patients can sleep well, and have a normal need for sleep. Therefore, they find it very difficult to wake up in the morning if they have only slept for a few hours. However, they sleep soundly, wake up spontaneously, and do not feel sleepy again until their next "night," if they are allowed to follow their own late schedule, e.g. sleeping from 4 am to noon.
 * Symptoms have been present for at least a month, and usually much longer.

The syndrome can develop suddenly or gradually.

DSPS is diagnosed by a clinical interview, actigraphic monitoring and/or a sleep log kept by the patient for at least three weeks.

People with DSPS have at least a normal - and often much greater than normal - ability to sleep during the morning, and sometimes in the afternoon as well. In contrast, those with chronic insomnia don't find it much easier to sleep during the morning than at night. Another important difference is that the DSP individual falls asleep at more or less the same time every night, and sleep comes quite rapidly if the person goes to bed near the time he or she is usually falls asleep. Young children with DSPS resist going to bed before they are sleepy, but the bedtime struggles disappear if they are allowed to stay up until the time they usually fall asleep.

Additional symptoms
In addition to the main symptoms of DSPS, most people with DSPS also have some or all of the following features:


 * DSP individuals are night owls. They feel most alert and say they function best, are most creative, etc. in the evening and at night.
 * They usually have tried many times to change their sleeping schedule. Failed tactics to sleep at earlier times may include relaxation techniques, early bedtimes, hypnosis, alcohol, sleeping pills, dull reading, and folk remedies. They often have asked family members to help wake them in the morning, or they have used several alarm clocks. Or family members - especially parents - have tried to get them up on time.
 * Symptoms often begin in adolescence, childhood, or infancy.
 * They are sleepy during the day, especially in the morning, if they have had to get up early. They sleep in on weekends (often past noon and for more than 10 hours) to make up for not getting enough sleep during the rest of the week. Some people with DSPS take naps during the day and feel refreshed afterwards.
 * Many people with DSPS need at least 30 minutes to fall asleep, even when they go to bed at a time that is realistic for them.
 * Some people with DSPS have occasional, sudden, and temporary reversions to sleeping at earlier times.

People with DSPS show delays in other circadian markers, such as melatonin-secretion and core body temperature minimum, that correspond to the delay in the sleep/wake cycle. Sleepiness, spontaneous awakening, and these internal markers are all delayed by the same number of hours.

Causes
DSPS is a disorder of the body's timing system - the biological clock. It is believed to be caused by a reduced ability to reset the body's daily sleep/wake clock in response to time cues in the person's environment. For example, individuals with DSPS might have an unusually long circadian cycle, or might have a reduced response to the re-setting effect of light on the body clock.

DSPS patients have difficulty falling asleep and difficulty waking because their biological clocks are out of phase with the sleeping and waking times they try to carry out. Normal people who do not adjust well to working a night shift have similar symptoms.

In most cases, it is not known what causes the biological clocks of DSPS patients to become abnormal. DSPS has in some instances followed an illness or head injury, and might run in families. A growing body of evidence suggests that the problem is genetic.

Differentiation from non-24-hour sleep-wake syndrome
Non-24-hour sleep-wake syndrome is a related circadian rhythm sleep disorder. People with non-24-hour sleep-wake syndrome syndrome will also typically sleep later than society considers normal. However, people with DSPS do, by definition, live on a 24 hour day. They can go to bed at the same time every morning and get up at the same time each day. There have been some reports of DSPS developing into non 24-hour sleep-wake syndrome.

Impact on patients
For most sufferers, DSPS is evident from infancy and is a lifelong condition. For some the onset is in adolescence. It sometimes becomes less severe later in life.

Lack of public awareness of the disorder contributes to the difficulties experienced by DSPS patients and their families. Parents may find themselves chastised for not giving their children acceptable sleep patterns, and schools are generally uncooperative in helping children. Children may be inappropriately treated for insomnia and even ADHD or ADD. People with DSPS are commonly stereotyped as undisciplined or lazy.

Attempting to force oneself through 9–5 life with DSPS has been likened to constantly living with 6 hours of jet lag. Often, sufferers manage on a few hours sleep a night during the working week, then "catch up" by sleeping excessively at the weekend and sometimes by means of afternoon or evening naps, with inevitable effects on their social lives and, after decades, on their general health.

Treatments
Treatment for DSPS is specific. It is different from treatment of other types of insomnia, and recognizes the patient's ability to sleep well while addressing the timing problem.

Mild cases of DSPS can be controlled by waking up and going to bed 15 minutes earlier every day until the desired sleep schedule is reached, and then maintaining a strictly regular sleep/wake schedule seven days a week. More severe cases are treated by the methods discussed below. No particular treatment relieves DSPS in all cases.

Before starting DSPS treatment, patients are often asked to spend a week sleeping regularly, without napping, at the times when the patient is most comfortable. It is important to start treatment well-rested.

Treatments that have been reported in the medical literature include:
 * Light therapy (phototherapy) with a full spectrum lamp or portable visor, usually 10000 lux for 30-90 minutes in the morning.
 * Chronotherapy, which consists of resetting the circadian clock by going to bed several hours later each day for several days.
 * A small (~1mg) melatonin supplement taken an hour or more before bedtime may be helpful in establishing an earlier pattern, especially in conjunction with bright light therapy at the time of spontaneous awakening. Side effects of melatonin may include disturbance of sleep, daytime sleepiness and depression. The long-term effects of melatonin administration have not been examined, production is unregulated and in some countries the treatment is not used.
 * Some claim that large doses of vitamin B12 help normalize the onset of sleepiness, but little is known of the effectiveness of the treatment.
 * A treatment option which shows promise is Ramelteon, a recently-approved drug which in some ways acts as a synthetic melatonin. Production of ramelteon is as regulated as any other prescription medicine, so it avoids the problems of variable purity and dosage with melatonin supplements.
 * Modafinil is approved in the USA for treatment of Shift-work sleep disorder (SWSD), which shares some characteristics with DSPS, and a number of clinicians are prescribing it for DSPS patients.

Forcing a patient to go to sleep early, for example by the use of sedatives or "sleeping pills", and forcing early rising does not result in adaptation to the new sleeping pattern. Some sufferers report that sedatives are ineffective and can even exacerbate the problem.

Prognosis
There is no known cure for DSPS; treatments are only be a way to manage the condition. For many sufferers, no normalization is possible. These people either adjust their social and work patterns, or suffer from chronically insufficient sleep.

DSPS and depression
In the DSPS cases reported in the literature, about half of the patients have suffered from clinical depression or other psychological problems. The relationship between DSPS and depression is unclear. The fact that some DSPS patients are not depressed indicates that DSPS is not merely a symptom of depression. Even in depressed patients, treatment methods such as chronotherapy can be effective without directly treating the depression.

It is conceivable that DSPS often has a major role in causing depression, because it can be such a stressful and misunderstood disorder. A direct neurochemical relationship between sleep mechanisms and depression is another possiblity.

DSPS patients who also suffer from depression should seek treatment for both problems. There is some evidence that effectively treating DSPS can improve the patient's mood and make antidepressants more effective. In addition, treatment for depression can make patients more able to successfully follow DSPS treatments.