Summary

 Background: Insomnia is the most common sleep disorder. Treatment options are improved sleep hygiene, relaxation, cognitive behavioral therapy, and medications. Studies examining the effect of hypnotics on insomnia reported that placebo had a substantial beneficial effect. Objectives: To evaluate whether placebo is an effective treatment for insomnia.

Methods: We assessed 25 patients with insomnia who were enrolled in a hypnotic study but prior to the study were asked to undergo two full nights in lab polysomnography studies: with and without a placebo. Although they were not explicitly told that they were receiving a placebo, the participants knew that the results of these studies would determine whether they met the criteria to participate in the pharmaceutical study.

Results: Although the participants acknowledged that they were given a placebo, almost all measures of their sleep improved. With placebo, sleep latency was shortened from 55.8 ± 43.5 to 39.8 ± 58.5 minutes (P < 0.05); total sleep time was extended from 283 ± 72.5 to 362.9 ± 56.3 minutes, and sleep efficiency improved from 59.57 ± 14.78 to 75.5 ± 11.70% (P < 0.05). Interestingly, placebo had no effect on the relative sleep stage distribution (percentage of total sleep time), except for a trend toward increased percentage of REM[1] sleep.

Conclusions: Our findings how a clear and significant beneficial effect of placebo on insomnia, despite participants' understanding that they were receiving placebo. These results emphasize the importance of the patients' perception and belief in insomnia treatment, and suggest that in some cases placebo may serve as a treatment.