Delayed sleep phase syndrome (DSPS) is one of many circadian rhythm sleeping disorders, and is the most prevalent of all such disorders. People with delayed sleep phase have a natural inclination to go to bed later and wake up later than what is typically considered normal. It is the opposite of advanced sleep phase, in which people go to bed and wake up earlier than normal. People with delayed sleep phase generally go to bed in the early morning hours, from 1 am to 4 am, and wake up later in the morning, from 8 am to 11 am. Socially active people, and those considered ‘night owls’, who feel more awake or sharper during the evenings, are at a high rate of having or getting this disorder.