Delayed Sleep Phase Syndrome

Have you ever thought about why some people don't sleep until morning? It might be that they're afflicted by delayed sleep phase syndrome.
Delayed Sleep Phase Syndrome

Last update: 17 December, 2019

People with delayed sleep phase syndrome are unable to adapt to socially established sleep-wake schedules. Due to the lack of information and understanding of this disorder, people around them often consider them lazy.

The sleep-wake pattern follows a circadian rhythm; that is, it fluctuates regularly every 24 hours. An internal biological clock determines this oscillation and certain external synchronizers also help it.

Social elements, such as working hours or meals, serve to more accurately adjust sleep and wakefulness hours. However, the most powerful external synchronizer is the light-dark cycle.

The problem arises when there’s a mismatch between the body’s circadian system and the requirements of a person’s environment. In the case of delayed sleep phase syndrome, a person’s usual nighttime sleeping period is behind when compared to the standard time.

Individuals with this ailment feel the need to lie down and get up (chronically) at least two hours later than the rest. This lag is more common during adolescence; however, the prevalence in adults is significant.

When the daily duties force this kind of person to follow a standard schedule, they’ll be chronically sleep-deprived because they’re unable to fall asleep at the specific time that such schedule dictates. Thus, this translates into drowsiness and fatigue during the day that will affect the school and work performance of those afflicted by this disorder.

During holidays or vacations where they can freely choose and delay their sleep schedules, it becomes adequate both in quantity and quality. Insomnia and difficulty getting up both disappear and the person enjoys a restful rest.

Differential characteristics of delayed sleep phase syndrome

Some of the most common characteristics of delayed sleep phase syndrome are:

  • The person may maintain adequate sleep hygiene and still won’t be able to sleep at the desired time.
  • There are no personal or work situations or anxious or depressive symptoms that might encourage a person to fall asleep.
  • Once the person afflicted by this syndrome falls asleep, they have no difficulty staying asleep. They sleep continuously and there’s no waking up — a sign of sleep-maintenance insomnia.
  • Due to lack of sleep, drowsiness and a decrease in alert levels occur during the first half of the day. This situation improves as the maximum wakefulness point approaches, which for these people is towards the sunset.
  • Being able to choose their preferred hours, a person with this condition falls asleep without difficulty and wakes up rested.

Treatment of delayed sleep phase syndrome

Behavioral intervention

The first step is an intervention in an individual’s usual behavior. They must try to maintain the best possible sleep hygiene and take care of the environment in which they sleep. Also, they must avoid the use of stimulants and be mindful of the type of activities they do before bedtime.

In this regard, it’s of utmost importance for the person afflicted to have a fixed sleep schedule. They must follow this schedule every day without changing it on holidays or vacations. In addition, they must maintain this habit even after they reach their goal in order to avoid relapses.


Reducing exposure to light at dusk and increasing it in the morning can also help produce a breakthrough in their biological clock. To do so, it’s important for them to use dim light during the last hours of the day, as well as get rid of curtains or blinds.

Similarly, they must sleep without curtains or blinds so that there’s greater exposure to sunlight in the minutes that follow their wake up time.


The administration of melatonin (1-5 mg) a few hours before going to sleep helps advance the wake-sleep cycle. It increases its effectiveness when used along with phototherapy.


This procedure consists of gradually delaying bedtime and getting up. So, the person afflicted goes to bed later each day until they achieve the desired sleep schedule. Thus, their main challenge is to keep it up from there.

The main difficulty lies in the fact that they need several days of modification of their sleep schedule before they achieve a fit. Unfortunately, this is something that can interfere with work or school responsibilities. In any case, it’s an alteration they have strategies against so it doesn’t become a disabling limitation on their daily routine.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Giménez Badia, S., Albares Tendero, J., Canet Sanz, T., Jurado Luque, M., Madrid Pérez, J. A., Merino Andreu, M., & Sellés Galiana, F. (2016). Trastorno de retraso de la fase del sueño y del despertar. Síndrome de retraso de fase. Pediatría Atención Primaria18(71), e129-e139.

  • Solari, B. F. (2015). Trastornos del sueño en la adolescencia. Revista Médica Clínica Las Condes26(1), 60-65.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.