Circadian Rhythm Disorder

As humans, we all have a natural internal body clock called the circadian rhythm. The circadian clock regulates all biological functions within a slightly longer 24-hour period, particularly our wake and sleep patterns. Our wake/ sleep pattern is set by light and darkness and daytime and evening hormones.

The Circadian rhythm sleep disorder is a misalignment with the natural timing of the body clock.

Factors that contribute to this are:

  • Shift work

Regular shift work changes the natural circadian timing affecting the ability to fall asleep or wake up at “normal” times. This type of work shifts the body clock. Rotational shifts are worse than doing the same night shift. This tends to have an accumulative sleep deprivation affect because although our sleep cycles remain relatively the same whether we sleep 7-8 hours in the day or night, the daytime sleep tends to be shorter and more disrupted due to external noise.

  • Frequent travel across time zones (Jetlag)

This affects people who travel across time zones causing a disruption in their body clock such as airline pilots. This affects their sleep patterns, quality of sleep, appetite, gastrointestinal dysfunction, mood disorders and daytime alertness.

  • Lifestyle habits

Poor sleep Hygiene can shift the body clock very easily. Those that stay up very late or sleep in till very late reset their body clock to those time periods. Although it can be done, they will find it difficult to change back to an earlier bedtime should their circumstances change (change of job). Retirees tend to develop poor habits due to the lack of


  • Delayed sleep phase Syndrome

This disorder shifts the circadian clock forward whereby a person goes to bed really late and struggles to get up at a socially acceptable time in the morning. They literally do not get sleepy till very late so going to bed early causes frustration further compounding the difficulty getting to sleep. This syndrome occurs naturally in teens and young adults but tends to sort itself in the mid-twenties unless there is a genetic or some other underlying factor.

  • Advanced sleep phase

This syndrome shifts the circadian clock whereby a person will go to bed earlier than socially normal and wake very early. This can affect the quality of sleep due to inadequate production of hormones such as adenosine (accumulates during the day to produce sleepiness at night) and melatonin (sleep hormone). Long term this will affect the ability to control weight and natural biological function.

The cause of this is not completely understood but scientists believe there may be a genetic link. Alcoholics usually present with this syndrome due to alcohol affecting REM sleep and causing early wakefulness.

 Risk factors

  • Age
  • Medical conditions
  • Gender
  • Genetics
  • Environment and career
  • Lifestyle habits

Treatment for all

 Healthy lifestyle habits

  • Light therapy
  • Medications such as melatonin
  • Chronotherapy: A behavioral technique in which a persons bedtime and rise time is systematically altered until the body clock follows a socially acceptable time frame

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