Watching TV 'Blocks Sleep Hormone In Children'

London Independent | June 28 2004

ROME -- Exposure to television can influence melatonin levels in children and possibly contribute to the premature onset of puberty, according to a study by scientists from the University of Florence.

The study found a 30 per cent increase in levels of the sleep-regulating hormone in children who had abstained from watching television for a week, the Rome daily La Repubblica reported yesterday.

The findings are based on a study of 74 children from the Tuscan town of Cavriglia who volunteered to forego television, video games and computers for a week last month in the interests of science. Aged between six and 12, the children normally watched an average of three hours' television a day. Urine samples taken at the beginning and end of the experiment showed a significant rise in melatonin levels, particularly among the younger children, by the end of the television-less week. As well as blacking out the video screens, parents were asked to reduce the intensity of artificial lighting in their homes during the experiment.

Melatonin is a hormone produced by the pineal gland, a pea-sized organ just above the middle of the brain. Exposure to light during the day inhibits its production, which normally begins around 9pm, with rising levels of melatonin in the blood making people feel sleepy. Scientists are less certain about the role of the hormone in regulating the onset of puberty, an issue the Florence researchers intend to pursue. In Western societies, the arrival of puberty has advanced by about a year since the 1950s, when television became common.