Children who watch a lot of television produce less melatonin, new research suggests – the “sleep hormone” has been linked to timing of puberty.

Scientists at the University of Florence in Italy found that when youngsters were deprived of their TV sets, computers and video games, their melatonin production increased by an average 30 per cent.

“Girls are reaching puberty much earlier than in the 1950s. One reason is due to their average increase in weight; but another may be due to reduced levels of melatonin,” suggests Roberto Salti, who led the study. “Animal studies have shown that low melatonin levels have an important role in promoting an early onset of puberty.”

Salti and colleagues studied 74 children aged between six and 12 years old, who normally watched an average three hours of television in the evening between 2000 and midnight. The youngsters, from the Tuscan town of Cavriglia, were encouraged to watch more TV than usual for a week preceding the study.

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