Sleepwalking associated with hyperthyroidism.

OBJECTIVE: To report several cases of hyperthyroidism in patients presenting with the unusual symptom of sleepwalking and to discuss the possible pathophysiologic basis for this novel association.

METHODS: After encountering and reporting the first case of new-onset somnambulism in a patient presenting with thyrotoxicosis at our institution, we routinely inquired about the sleep history of patients with thyrotoxicosis, questioning both the patients and family members when applicable. Those patients who actually had sleepwalking episodes coinciding with the onset of thyrotoxicosis underwent close follow-up, and the relationship between the sleepwalking and the results of thyroid function tests was analyzed. In addition, we reviewed the literature on psychiatric disorders and sleep problems, and the pathophysiologic rationale for a cause-and-effect relationship is discussed.

RESULTS: We collected 8 cases of patients with new-onset sleepwalking episodes that coincided with the start of thyrotoxicosis. The disappearance of the sleepwalking with successful achievement of euthyroidism supports a cause-and-effect relationship. This hypothesis is further supported by the absence of a family history, the adult onset, and the relapse of sleepwalking in 2 of the patients when their thyrotoxicosis became poorly controlled as a result of noncompliance with medications and its subsequent disappearance with reachievement of euthyroidism. Of note, such a presentation was seen only in patients with thyrotoxicosis caused by diffuse toxic goiter or Graves' disease and never in patients with other causes of thyrotoxicosis.

CONCLUSION: New-onset sleepwalking could be caused by thyrotoxicosis or, more specifically, by thyrotoxicosis resulting from diffuse toxic goiter. The mechanism is hypothesized to be related to the combination of prolongation of non-rapid eye movement sleep and the associated fatigue. Specific inquiry about this unusual presentation of thyrotoxicosis is encouraged, and more studies are needed to confirm and evaluate its extent.