The herb ashwagandha, which has been used for centuries in Indian folk medicine to promote sound sleep has been proven effective by Japanese researchers.

Ashwagandha (Withania somnifera) is a central herb in Ayurveda, the traditional home medicine native to India. Its Latin name — somnifera — means sleep-inducing.

Researchers at the University of Tsukumba studied the effects of various components of ashwagandha on mice by using a neurological test (EEG) to record activity in the brain.

A water extract of ashwagandha leaf, which was rich in the component triethylene glycol (TEG), significantly increased non-rapid eye movement (NREM) sleep. It also slightly changed rapid eye movement (REM) sleep.

An alcoholic extract containing active withanolides,  which are other active compounds in ashwagandha, showed no effect on sleep.

The sleep induced by TEG was similar to normal sleep. Furthermore, commercially available TEG also increased the amount of NREM sleep.

The researchers concluded that TEG is the active component that induces sound sleep, and that TEG can improve sleep without side effects. They believe their findings could revolutionize the natural plant-based therapies for insomnia and sleep-related disorders.

According to the Centers for Disease Control and Prevention, up to 70 million American adults have difficulty sleeping. Sleeping disorders increase with aging, and affect almost half of adults 60 and older.

Ashwagandha is available in capsules in health food stores.