Answer: 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,[1] and sometimes disappears in adolescence or early adulthood. It is usually treatable, but cannot be cured.