Circadian rhythm sleep disorders

Circadian rhythm sleep disorders are a of sleep disorder in which abnormalities in the timing of sleep appear.

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What is the circadian rhythm?

The circadian rhythm, sometimes referred to as the “body clock”, is the body’s natural sleep pattern, including feelings of drowsiness and alertness during the day. It naturally affects the body temperature, appetite, hormone secretion and alertness of the individual, all of which affect the timing of sleep.

A patient with a circadian rhythm sleep disorder cannot sleep because of work, study, or lifestyle and wakes up at times that correspond to their circadian rhythm. In most cases, if they can sleep according to their internal clock, they can get adequate sleep throughout the day; However, their daily commitments are out of sync with their circadian rhythms, making it difficult to fall asleep when they have time to sleep.

Delayed sleep phase disorder

Delayed sleep phase disorder is when a person’s internal clock is two or more hours later than normal, leading to delayed feelings of drowsiness and wakefulness about the external environment.

This typically means that affected people fall asleep after 1 a.m. and only wake up naturally in the late morning or afternoon. However, most people with this disorder have morning work or study obligations that reduce the length of time they sleep, which can lead to sleep deprivation and daytime sleepiness.

Light therapy and melatonin treatment can be helpful in bringing the sleep phase forward by up to two hours; however, these options may not be available for everyone to move their sleep phase to the normal schedule.

Advanced sleep phase disorder

Advanced sleep phase disorder is when a person’s internal clock is two or more hours earlier than normal, causing them to feel sleepy in the early evening and wake up earlier in the morning or at night.

This of circadian rhythm sleep disorder appears to be less common than the delayed phase, although this may be because most people with the disorder don’t experience negative symptoms if they can organize their activities to sleep earlier .


Free-running sleep disorder, also known as non-24 sleep disorder, occurs when a person is sleepy and falls asleep later each consecutive day because their circadian rhythm is longer than 24 hours.

This leads to a disturbed sleep cycle that is not tuned to natural changes in light, so that those affected sleep normally at night, while in others they can only fall asleep during the day. This disorder can be very distressing as it prevents those affected from performing normal daily activities such as work, study, relationships, and other commitments. Because of this, it is linked to isolation, poverty, and depression.

Irregular sleep-wake disorders

Irregular sleep-wake disorder involves more than normal sleep episodes, usually at least three in any 24-hour , occurring at different times each day. This type of sleep disorder is most common in the elderly with dementia, but it can also often be seen in children with developmental disabilities.

Sleep disorder when working shifts

Shift work sleep disorder is an extrinsic circadian rhythm disorder, that is, it is caused by external circumstances. People who work day and night alternating shifts are more likely to suffer from changes in their internal clock to an altered sleep pattern, although some people are more susceptible than others.

This sleep disorder can lead to difficulty falling asleep and chronic lack of sleep, including symptoms of daytime sleepiness and decreased performance.

Jet lag sleep disorder

Jet lag sleep disorder occurs when a person travels quickly through multiple time zones without their internal clock being able to adapt to the outside environment and light signals. This requires a shift in the sleep-wake rhythm and the circadian rhythm, which can take time and cause symptoms of drowsiness in the meantime. However, the body usually adjusts to the new time zone within a few days after the trip.


Treatment for circadian rhythm insomnia usually involves techniques to adjust the internal clock and sleep-wake cycle to bring them closer to normal. This can include:

  • Behavioral Therapy – It is recommended that affected individuals avoid naps, caffeine, and alcohol before bed.
  • Bright Light Therapy – This treatment option can be used to advance or delay the sleep cycle.
  • Dark Therapy – Dark Therapy can be used to block light stimuli during the night.
  • Pharmacotherapy – Pharmacological agents like melatonin or modafinil can be used to aid sleep.


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