Double-blind test on the efficacy of methylcobalamin on sleep-wake rhythm disorders.

The therapeutic effect of methylcobalamin (Met-12) on sleep-wake rhythm disorders was examined in a double-blind test. In the test group which was given a large dosage, a higher percentage of improvement was found compared to the control group with a small dosage, although the difference was not significant. The test group inconsistently showed significant improvement in both the sleep-wake cycle parameters and in clinical symptoms. The tendency was for the results to show a beneficial effect of Met-12 on rhythm disorders. However, because the percentage of improvement was low and significant improvement was inconsistent, Met-12 might be considered to have a low therapeutic potency and possible use as a booster for other treatment methods of the disorders.