Effect of yokukansan on psychophysiological insomnia evaluated using cyclic alternating pattern as an objective marker of sleep instability

In this open-label study using final evaluator blinding, the efficacy of yokukansan (YKS) was evaluated in six psychophysiological insomnia patients using the cyclic alternating pattern (CAP) method. YKS had no influence on objective sleep parameters by the Rechtschaffen & Kales method, but the CAP rate and CAP cycle frequency decreased significantly. In the subjective Visual Analog Scale test, significant improvement was seen in five items: tension, calmness, fatigue, heavy-headedness and lassitude. No adverse reactions were noted. YKS improved sleep quality without influencing sleep structure and showed no adverse reactions, suggesting that YKS is an effective antiinsomnia drug with good tolerability.