Insomnia Workup

Updated: Nov 27, 2017
  • Author: Jasvinder Chawla, MD, MBA; Chief Editor: Selim R Benbadis, MD  more...
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Workup

Approach Considerations

Insomnia is a clinical diagnosis. Diagnostic studies are indicated principally for the clarification of comorbid disorders.

Before therapy is instituted, most patients are asked to keep a sleep log for 2-4 weeks. This log, in which the patient records bed and wake times, sleep duration, and daytime naps and activities, gives a clearer picture of the degree of sleep disturbance and allows development of a tailored treatment.

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Studies for Hypoxemia

Patients with a history suggestive of chronic obstructive pulmonary disease (COPD) and insomnia should have oximetry or an arterial blood gas (ABG) test performed to determine whether they are hypoxemic. Insomnia in COPD frequently begins with the development of nocturnal hypoxemia, although nocturnal hypoxemia is not required for insomnia to occur. Oxygen therapy may improve insomnia but rarely eliminates it.

Nocturnal hypoxemia is present if the patient has daytime hypoxemia or, frequently, exercise-related hypoxemia. If the oximetry or ABG result is negative for hypoxemia, an exercise desaturation study or overnight oximetry may be helpful to determine whether the patient needs oxygen.

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Polysomnography

Polysomnography and daytime multiple sleep latency testing (MSLT) are not routinely indicated for the workup of insomnia. [1, 65] However, patients with a history suggestive of sleep apnea should be referred to a sleep center for polysomnography, as should patients who have precipitous arousals with violent or injurious behavior, as well as some patients with restless legs syndrome (RLS)/periodic limb movement disorder (PLMD). Treatment failure may also be an indication for polysomnography. [1]

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Actigraphy

For actigraphy, a portable device is worn around the wrist to record gross motor activity and light/darkness over extended periods. This study provides an indirect objective measure of sleep and wake time. Actigraphy has shown concordance with polysomnography in the assessment of total sleep time. [66] The role of actigraphy in insomnia evaluation has not been well established, but actigraphy can help document sleep patterns and circadian rhythms.

Distinguishing primary insomnia from circadian-rhythm disorders and identifying paradoxical insomnia is useful, particularly with insomnia that is refractory to treatment.

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Sleep Diary

A sleep diary is appropriate when a patient reports an irregular sleep schedule. Maintaining a sleep diary can be done in conjunction with wrist actigraphy. In the diary, patients should record estimates of the time at which they do the following:

  1. Go to bed
  2. Fall asleep
  3. Awaken during the night
  4. Lie in bed awake
  5. Get out of bed in the morning

Patients should also record when and how long they exercise, when they take medications, and when they consume caffeinated or alcoholic beverages. (Click on the image below to download a sample sleep diary form.)

Sleep diary. Sleep diary.

For diagnosis, the patient should maintain a sleep diary for 1-2 weeks. The 2008 American Association of Sleep Medicine (AASM) guideline recommends collection of sleep diary data both before and during active treatment and afterward if a relapse occurs or if the patient’s status needs to be reevaluated. [1] Although the sleep diary provides detailed information about sleep patterns, it can be confounded by the patient's subjective assessment of when they fall asleep and awaken during the night.

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Genetic Testing

If a patient with rapidly progressing insomnia has any first-degree relatives who died with insomnia, there may be concern for fatal familial insomnia (FFI). Genetic testing for this rare condition is available and consists of sequencing the PRNP gene. Brain imaging—specifically, positron-emission tomography (PET) to look for hypometabolism in the thalamus and cingulated cortex—may also assist in the diagnosis of FFI. [2]

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