Melatonin is found in large quantities in Feverfew, Tanacetum parthenium, a member of the Compositae (Daisy) family.
While most of the chemicals highlighted in this trail have primarily a defence function, melatonin helps regulate the plant's response to photoperiods (the length of night and day) and its ability to survive in harsh environments.
The compound is also found in animals, where the amount varies in cycles through the day. In mammals, melatonin is secreted into the blood by the pineal gland in the brain. It plays a part in regulating the sleep-wake cycle by chemically causing drowsiness and lowering body temperature.
Melatonin can be used to treat circadian rhythm sleep disorders, some types of insomnia and to counter jet-lag. It is involved in the mechanism by which some reptiles and amphibians change colour.
Feverfew, as the common name suggests, has long been used in herbal medicine as a treatment for fevers, and is being investigated as a treatment for migraine.