Efficacy and safety of herbal stimulants and sedatives in sleep disorders.

World-wide use of herbal medicines is increasing, following regulatory and manufacturing developments. Herbs are attractive alternative medications to many patients with sleep disorders, who may be averse to using conventional drugs. We review here the most common herbal stimulants and sedatives. Caffeine, in herbal teas, black tea, coffee, soft drinks and pharmaceuticals, is used widely to control sleepiness, but more research is needed on its use in sleep disorders. Ephedra, and its constituent ephedrine, are used in both stimulant and weight loss preparations, sometimes with caffeine; safety concerns have arisen with this practice. Yohimbe is another herb used in stimulant and body-building preparations which has safety concerns. Asian and Siberian ginseng have been traditionally used for fatigue, and have some supportive experimental evidence for this use. Herbal sedatives also have some evidence for efficacy; the observations that certain plant flavonoid compounds bind to benzodiazepine receptors adds interest to their use. Valerian and kava have received the most research attention; both have decreased sleep onset time and promoted deeper sleep in small studies, and kava also shows anxiolytic effects. German chamomile, lavender, hops, lemon balm and passionflower are reputed to be mild sedatives but need much more experimental examination.