When internal sleep pattern of body is disturbed or delayed, it is known as delayed sleep phase (Delayed sleep-wake phase sleep disorder). It happens when the circadian rhythm or sleep clock is two or more hours delayed than the normal one.


Diagnosis requires a detailed physical examination, medical and family history and some tests:

  • Sleep diary: note the sleep and wakeup times to help the doctor know about sleep patterns.
  • Actigraphy: a device that notes the sleep and wake patterns at home.
  • Polysomnogram: the test is done at a sleep center where there are monitors attached to the person to note the brain activity, movement of the eye, levels of oxygen, breathing patterns while sleeping overnight.

A plan is to be prepared by doctor and patient which may include:

  • Light therapy: circadian rhythm can be improved with more exposure to light in the morning.
  • Melatonin Supplements: these medications taken in the evening help correcting the circadian rhythm
  • Chronotherapy: in this therapy, a sleep schedule is given in which time of going to bed is delayed until the time that is desired is achieved. That should be maintained after then.
  • Improving sleep habits: avoid taking caffeine and other awakening substances at night, avoid alcohol and tobacco containing substances. Exercise should be done in the morning only, not near bedtime.
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