THERE are some headlines that have me reaching for a gun. “Turn off the TV, girls, or risk early puberty” this week had my trigger finger itching.

The psychologist Dr Aric Sigman claimed that watching TV was responsible for the increasingly early onset of puberty. As evidence, he cited a number of studies showing lower levels of the hormone melatonin associated with staring into a bright screen in the evening, a time of day when it should be increasing. Since melatonin levels affect puberty more in girls than in boys, he opined, it is clearly the reason that girls have been reaching puberty earlier since the 1950s.

Nice try, but no coconut.

This work reminds me of those Victorian tracts that blamed all the ills of the age on the advent of the railways. After a few years it became clear that the age of mass rail travel was not causing a national malaise because Britons were demonstrably healthier than in the decades before. So something new had to be found to be the health bogeyman. Electricity in the home fitted the bill nicely, being blamed as the cause, among other things, of “nervous debility”.

Every age finds something to blame for its ills. Today (along with environmental chemicals) it’s telly, which is making us fat, sleepless, mentally dull and is taking girls wickedly into womanhood long before their time.

In fact, the age of a first period (an indicator for puberty) has been falling since the last century, way before the age of TV. The average age at first period was 16 to 17 in Victorian times and has fallen ever since to its present level of about 12. A study of Glasgow students born between 1919 and 1952 showed that the average age of first period dropped from 13½ for those born at the start of the study, to 12½ born towards the end of the study.

Why? Before puberty can occur in a girl she must have enough body fat and be adequately nourished, getting enough iron in particular. So earlier periods are a sign of good nutrition rather than evil television.

And levels of melatonin alone don’t dictate the course of puberty, as a recent study from Spain has shown. It is true that melatonin does funny things at puberty, which accounts for teenagers’ weird sleep patterns. But the light-from-TV theory has to go out of the window. Actually, the age at which periods start is not falling now, but seems to have stabilised in Britain, as it has done in other European TV-watching countries. We will have to find something else to blame for our early puberty, spots, obesity and cancer.

So lay off the TV, OK?

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