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Section 12: Information that Indicates Circadian Rhythm Sleep Wake Disorders

DSM-5-TR Code: G47.21   Delayed Sleep Phase type


Common Specifiers:

  • Familial
  • Overlapping with non-24-hour sleep-wake cycle

DSM-5-TR Code: G47.22    Advance sleep phase type


Common Specifiers:

  • Familial

DSM-5-TR Code: G47.23    Irregular sleep-wake type

DSM-5-TR Code: G47.24    Non-24-hour sleep-wake type

DSM-5-TR Code: G47.25    Shift work type

DSM-5 Code: G47.20    Unspecified type


Common Specifiers (All Types):

  • Episodic
  • Persistent
  • Recurrent

Prevalence (All types combined): 0.17-0.60%

Can this disorder legitimately be diagnosed by a Master’s level clinician?      Yes, with caution when no other evidence presents itself as being a likely cause of the sleep disturbance, and the diagnosis should probably be confirmed by a medical professional if additional intervention is necessary. 

As has been noted in this course, there is a quite complicated chemistry of the sleep-wake cycle, involving the timely release of certain chemicals in the brain and body in order to fall and stay asleep, and certain chemicals in order to become and stay awake. There is a rhythmic quality to these chemical releases that follows, more or less, a 24-hour cycle. Certain chemicals are timed be released about the time a person is ready to go to bed, and certain chemicals are timed to be released about the time a person needs to get up to start his/her day. Derived from the Latin word for “day”, this is called a circadian rhythm.

While the physiological systems that run the circadian rhythm are generally well wired to run this cycle with clocklike consistency, there are also some features built in to create some flexibility. Some people need to stay awake late at night to work the night shift. Some people travel by plane halfway around the world - over several time zones - for work or vacation. Mechanisms need to be available to create shifts in this circadian rhythm to allow people’s clocks to be reset, allowing them to be awake and alert when this is called for, and sleeping soundly when it is time to get rested and restored.

One of the primary driving factors involved in the setting and re-setting of the circadian rhythm is bright light. When light hits the retina in the back of a person’s eye, it triggers the release of chemicals that send messages to areas of the brain associated with the circadian rhythm, essentially saying that it is morning and time to get awake and alert. If a person is on a regular day-night wake-sleep schedule, light first thing in the morning reinforces and re-establishes the circadian rhythm, keeping it on a good schedule.

If this light is the sun rising in a different time zone after an overnight plane flight, then the message helps to begin to create a shift in the circadian rhythm to get the person on the new 24-hour clock in the different time zone. For many people, it will take a few days for the new schedule to be fully established, but the inner body clock will adjust if the person is conscientious in getting up in the morning and exposing his/her eyes to bright light.

However, if the light is coming from a 100-watt lightbulb, or a bright television screen or computer monitor right before someone is getting ready to fall asleep, then the chemical messages can work against the other chemicals being released that are gently pushing the person towards getting a good night’s sleep. Depending upon how sensitive some people are to being exposed to light and how strong the release of the alertness provoking chemicals, this late night light can interfere with a person’s circadian rhythm and set up a sleeping disorder.

There are people who adapt very easily and quickly with these kinds of circadian rhythm challenges, who can work a night shift with very little problem and get a good night’s sleep – in a dark room - when most people are wide awake. But there are also people who do not have much flexibility when it comes to changing their sleep schedule, who respond poorly to night shift (shift work type), or changes in time zones.

There are also people whose circadian rhythms, for a variety of reasons, simply do not work as they should. For instance, persons who are completely blind, do not receive the retinal messages from morning light. Their body clocks do not get ongoing feedback to help their circadian rhythms stay on schedule. They may struggle to stay on a 24-hour schedule, as their biological clocks work under different time frames (non-24-hour sleep-wake type).

There are also people whose clocks tend to try to move forward (delayed sleep phase type), or back (advanced sleep phase type), on a nightly basis. They have a difficult time aligning their circadian rhythms with the 24-hour clock under which societies run. There are still other persons whose circadian rhythms do not seem to have a predictable regularity to them, and they may get sleepy and alert at relatively unpredictable times (irregular sleep-wake type).

What will be seen in common among all of these different types of circadian rhythm sleep-wake disturbances is a degree of sleep deprivation and the corresponding physical and emotional correlates. They will all look and feel tired.

While it is certainly possible for Master’s level mental health clinicians to gather sufficient information about the client’s sleep disturbance to make a diagnosis of these different types of disorders, it is generally wise for the clinician to have this diagnosis confirmed by a medical professional and to engage in close coordination with the medical professional in terms of treatment options. The client’s primary care physician may feel comfortable taking the lead in terms of strategies and/or medications to help the client re-establish a viable sleep cycle to fit his/her work and home life, or may decide that a referral to a sleep specialist is recommended.

There are circumstances where a client may have such extreme difficulties with their sleep-wake cycle that it may represent a legitimate threat to their health or well-being. There are individuals who simply are not physiologically capable of working the night shift because their sleep-wake mechanisms lack the flexibility to adapt their circadian rhythms to a reversed day-night schedule.

These individuals may seek to have reasonable accommodations put into place by their place of employment and ask their medical providers to supply evidence in support of this position. Under those conditions, it is recommended that mental health clinicians err on the side of caution and allow a sleep specialist to provide the expert information to advocate for that accommodation.