Sleep Disorder – Delayed Sleep Phase Syndrome(DSPS)
Delayed sleep-phase syndrome (DSPS), also known as delayed sleep-phase disorder, is a chronic disorder of sleep timing. People with DSPS tend to fall asleep at very late times, and also have difficulty waking up in the morning.
Often, people with the disorder report that they cannot sleep until early morning, but they fall asleep at about the same time every “night”, no matter what time they go to bed. Unless they have another 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 time for a typical school or work day 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 a.m. to noon.
The syndrome usually develops in early childhood or adolescence, and sometimes disappears in adolescence or early adulthood. It can be to a greater or lesser degree treatable, but cannot be cured. People with DSPS tend to be extreme night owls. They feel most alert and say they function best and are most creative in the evening and at night. DSPS patients cannot simply force themselves to sleep early. They may toss and turn for hours in bed, and sometimes not sleep at all, before reporting to work or school.
By the time DSPS patients seek medical help, 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 home remedies. DSPS patients who have tried using sedatives at night often report that the medication makes them feel tired or relaxed, but that it fails to induce sleep. They often have asked family members to help wake them in the morning, or they have used several alarm clocks. As the syndrome is most common in adolescence, it is often the patient’s parents who initiate seeking help, after great difficulty waking their child or teenager in time for school.
DSPS is a disorder of the body’s timing system – the biological clock. 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.
People with normal circadian systems can generally fall asleep quickly at night if they slept too little the night before. Falling asleep earlier will in turn automatically advance their circadian clocks. In contrast, people with DSPS are unable to fall asleep before their usual sleep time, even if they are sleep-deprived. Research has shown that sleep deprivation does not reset the circadian clock of DSPS patients, as it does with normal people.
People with the disorder who try to live on a normal schedule have difficulty falling asleep and difficulty waking because their biological clocks are not in phase with that schedule. Normal people who do not adjust well to working a night shift have similar symptoms.
People with the disorder also show delays in other circadian markers, such as melatonin-secretion and the 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. Non-dipping blood pressure patterns are also associated with the disorder when present in conjunction with socially unacceptable sleeping and waking times.