Another grape excuse to hit the bottle (press release)

The discovery of melatonin in grape skin could explain why so many of us hit the bottle in the evening to wind down after a day's hard slog. 'The melatonin content in wine could help regulate the circadian rhythm [sleep-wake patterns], just like the melatonin produced by the pineal gland in mammals,' says researcher Iriti Marcello at the University of Milan.

Until recently, melatonin was thought to be exclusively produced by mammals but has recently been discovered in plants. It is thought to have antioxidant properties. Iriti's study discovered high levels of melatonin in Nebbolo, Merlot, Cabernet Savignon, Sangiovesse and Croatina grape varieties.

Iriti's team have also shown that melatonin content can be enhanced in grapes by treating vines with a plant vaccine Benzothiadiazole.

Richard Wurtman of the brain and cognitive science department at MIT is unconvinced, however, and believes further research is needed to determine whether the compounds discovered are melatonin, or something very similar.