Objective Diagnosis of Circadian Rhythm Disorders

Circadian sleep-wake disorders are common. Because they represent conflict between the timing of the patient's endogenous rhythms and desired timing of sleep, the presenting complaints may include both difficulty of sleep initiation or maintenance and undesired or unplanned daytime or early evening sleepiness. Therefore, circadian disorders may be misdiagnosed as either a primary insomnia or a hypersomnia disorder, depending on which complaint is more troublesome for the patient. Objective information about sleep and wake patterns over long periods is crucial for accurate diagnosis. Actigraphy provides long-term information about the rest/activity pattern about an individual. However, caution should be applied in interpretation of the results because the information provided only includes information of movements, and activity is only an indirect circadian phase marker. Timing of light and melatonin therapy is critical for successful treatment of circadian rhythm disorders. Therefore, results of actigraphy are useful and should be used in conjunction with additional measurements, including 24 hours sleep-wake history, sleep log, and melatonin measurements.