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Circadian Rhythm Sleep Disorder Due to Medical Condition

What is it?

This disorder describes a group of different circadian rhythm sleep disorders (CRSDs) that are directly caused by a specific medical condition. People with these disorders have sleep times that seem to be out of alignment. Their sleep patterns do not follow the “normal” sleep times at night.

If the medical condition did not exist, then the CRSD would not be present. The medical condition is the identifiable cause of the body clock problem.

The medical condition can produce any of the abnormal timing patterns seen with these circadian rhythm disorders:

Delayed sleep phase disorder
You fall asleep late (for example, between 4 a.m. and 6 a.m.) every night. As a result you awaken at noon or in the afternoon every day.

Advanced sleep phase disorder
You fall asleep early (for example at 6 p.m.) every night. As a result you awaken early every day (for example at 2 a.m.).

Irregular sleep-wake rhythm
Your sleep pattern is broken up into short pieces. You sleep off and on in a series of naps over a 24-hour period.

Free-running (nonentrained) type
Your sleep time happens later and later every day.

CRSD due to medical condition is the diagnosis only if there is a specific medical condition that keeps you from being able to sleep during normal times. If the medical condition did not exist, then you would sleep during normal hours.

Who gets it?

The rate at which this disorder occurs varies with the type of medical condition that is involved. Changes in the timing of sleep are reported for several medical conditions. Some examples of these conditions are:

  • Dementia
    Circadian rhythm sleep problems are common in people with dementia. With dementia, the natural circadian rhythm becomes weaker. As a result, sleep may occur at different times or in pieces.

    Family may notice that the person becomes agitated or wanders around during the evening and at night. This is called sundowning. Awakenings, poor sleep, and frequent daytime naps are common.
  • Other sleep disorders such as sleep apnea are also more common in people with dementia. These disorders can cause added sleep problems at night and sleepiness during the day.
  • Movement disorders like Parkinson disease
    Sleep fragmentation and frequent awakenings are common in people with Parkinson disease. Sleep appears to occur at the wrong times. Parkinson patients may have insomnia at night and sleep attacks during the day. Tremor usually decreases but can continue during sleep and during awakenings.

    Other sleep disorders can also cause sleep problems for Parkinson patients. They are at increased risk for these problems:
  • Leg kicking (see periodic limb movement disorder)
  • Dream enactment (see REM Behavior Disorder)
  • Sleep apnea

    Demented patients with Parkinson may experience hallucinations.

    Also, certain Parkinson medications are reported to increase insomnias. Other medications increase daytime sleep attacks.
  • Blindness
    Three out of four blind people have sleep complaints and nearly half have ongoing sleep cycle problems. This is because light is important for the brain’s clock to work properly.

    Blind people with free-running (nonentrained) type have a unique sleep cycle problem. Their sleep time continues to get later and later every day. Any other sleep cycle problems related to blindness are in the category of CRSD due to medical condition.
  • Hepatic encephalopathy
    This most often occurs when you have had cirrhosis, a form of liver disease, for a long time. Toxins enter your bloodstream, causing confusion and behavioral changes. Insomnia and sleepiness are common in people with hepatic encephalopathy and with liver cirrhosis. Delayed sleep phase disorder may be seen in these people.

How do I know if I have it?

  1. Do you sleep at the wrong time because of a medical condition?
  2. Were you a normal sleeper before this medical condition appeared?

If your answer to these questions is yes, then you might have circadian rhythm sleep disorder due to medical condition.

Do I need to see a sleep specialist?

Yes. You should seek a doctor’s advice. This disorder can cause problems with work and family. You are asleep or are awake at times that are different from family and friends. You would have trouble maintaining relationships and responsibilities.

Having this disorder may make you home bound and isolated. Being home bound can make this condition worse. Because sleep time is out of line with others, some people try behaviors or medicines that might worsen this condition. They may get into trouble if they try to fix this problem on their own by taking more pills or alcohol.

People with dementia are unable to seek help for themselves.

What will the doctor need to know?

The doctor should ask you about your medical, neurologic, and sleep symptoms. The doctor also should ask you about your medications, alcohol, and your family history. Be sure to inform him or her of any past or present drug, alcohol, and medication use. Also tell the doctor if you have ever had any other sleep or neurological disorders.

The doctor should do a thorough medical and neurological exam.

You will be asked to complete a sleep diary to record your natural sleep and wake up times over several weeks. You may need to record the timing of any medications and the timing of medical or neurological symptoms. You may be asked to rate your sleep with the Epworth Sleepiness Scale.

Will I need to take any tests?

The diagnosis of CRSD due to medical condition is made clinically and with the use of the sleep diary. You may be asked to wear an actigraph. This is a device that records inactive and active episodes over a period of one to two weeks. An actigraph looks like a funny wrist watch and you wear it day and night.

Other testing methods to measure body temperature or melatonin levels may be used. Most often these methods are used for research.

Your doctor may suspect that a neurological condition or another medical problem is involved. In this case, you may be asked to have blood testing performed. You may also need a CT scan or an MRI.

Certain medical conditions also can increase your risk for other sleep disorders such as sleep apnea. An overnight sleep study is usually not needed to detect a CRSD. You may need to do a sleep study if you are at risk for other sleep disorders. The sleep study is called a polysomnogram. It charts your brain waves, heart beat, muscle activity, and breathing as you sleep. It also records how your arms and legs move. This shows if there are other sleep disorders that are causing or increasing your sleep problems. Examples include sleep apnea and periodic limb movement disorder.

How is it treated?

Treatment for CRSD due to medical condition is aimed at helping you to have one long sleep time at night and one long awake time during the day.

The doctor likely will also recommend good sleep behaviors for you to follow. These will improve your circadian rhythm. Good sleep hygiene is important to help you keep one main sleep time. Light, exercise, and other scheduled activities increase stimulation to reset the sleep clock in the brain. Education and behavioral counseling can be helpful. Your doctor may monitor your progress having you complete sleep logs during treatment. The doctor also may want to change medications for your medical problem. The doctor may choose medications that also help you sleep better at night and stay awake during the day. As research studies continue, more information will become available about the causes and other future treatments of this sleep disorder.

By Sharon L. Schutte-Rodin, MD
Updated March 27, 2006


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