Home » Sleep Disorders » Irregular Sleep-Wake Rhythm
November 2020 |  Reviewed by:  Shelley Hershner, MD and John Saito, MD

What is irregular sleep-wake rhythm disorder?

Irregular sleep-wake rhythm disorder (ISWRD) is one of several circadian rhythm disorders.

Normally, people are awake and asleep in rhythm with their biological clock. This is known as the circadian rhythm. It typically is a cycle that spans 24 hours and synchronizes to a 24-hour day.

If you have ISWRD, then you show no clear circadian rhythm. You struggle with wakefulness during conventional sleeping hours and sleepiness during the daytime. Your sleep and wake times show no clear pattern.

People with ISWRD may sleep off and on in a series of naps over a 24-hour period. This is similar to infants who may sleep for a few hours and then be awake for a few hours. By definition, to have ISWRD means you must have at least 3 sleep periods within a 24-hour period.

During the day, it may seem like you are sleepy because you nap so much. During the night, it may seem like you have insomnia because you are awake for long periods of time. There is not one main sleep time that occurs at any time of the day or at night. If you add up all of your sleep times, your total sleep time may not be normal for your age.

What are symptoms of irregular sleep-wake rhythm disorder?

Someone with ISWRD may:

  • Sleep off and on in a series of naps during the day and at night
  • Have no regular pattern of when they sleep and are awake
  • Have a hard time sleeping well, or are very sleepy when they are awake
  • Have a total sleep time that is not normal for their age

What are risk factors for irregular sleep-wake rhythm disorder?

ISWRD is rare. We do not even know how many people have it. It is believed that some people may have it because they have a weak body clock. This may happen in neurological conditions like:

  • Dementia
  • Brain damage
  • Mental health disorders

This can also happen in people who do not have a neurological problem. There are conditions that may make it easier for this problem to occur. Daily light and other activities are important in resetting our sleep clocks. Bad sleep habits may allow this disorder to occur in people who have weaker clocks. This is especially true for people who do not get en