[Valerian as a sleeping aid?].

BACKGROUND: Valeriana is a herbal over-the-counter drug, in Norway mainly used for insomnia. It is estimated that in Norway only, annual sales of valeriana amount to NOK 20 m. With this considerable consumption in mind, we wanted to review the scientific basis for valeriana as a sleep aid. MATERIAL AND METHODS: Through a literature search we identified 18 experimental studies examining the effects of valeriana on human sleep. RESULTS: The majority of studies reported positive effects of valeriana on subjective sleep parameters. Objective sleep measures yielded inconsistent results. All studies covered a short period of time. Few side effects of valeriana were reported. Only two studies compared valeriana to established hypnotics. INTERPRETATION: We conclude that valeriana may have some hypnotic effect. Long-term studies are clearly lacking, as well as studies comparing valeriana to well-established drug treatments for insomnia.