ONE of the few scientific facts I can easily remember, apart from the theory of relativity and Boyle’s second law of thermodynamics (naturally), is that nearly half of your body heat is lost through your head.

A hat, therefore, is not just a natty piece of headgear, but an essential part in one’s personal stance to stop wasteful bodily energy emissions and cut down on global warming in a single fell swoop.

But now it seems I’ll have to go looking for a third scientific fact to delight and enlighten strangers at dinner parties.

The old heat loss through the head is nonsense, according to leading bonce boffins. As a modern myth, it appears that this is indeed extremely modern. The hat-wearing advice has been trailed back to a 1970 US Army survival manual, which publicised the alarmist information that up to 45% of body heat was lost from the head.

This disinformation is believed to have started from a mistaken interpretation of a somewhat half-baked scientific experiment conducted by the US military in the 1950s. Volunteers were dressed in Arctic survival kit and exposed to extremely low temperatures. Surprise, surprise, because their heads were the only parts of their bodies left uncovered, most of the heat was lost through their heads.

Yet, as the latest researchers, Rachel Vreeman and Aaron Carroll, from Indiana State University, explain in the British Medical Journal, if this premise was true, then humans would be just as cold if they went without their hat, as they would if they went without their trousers.

The nub of the problem lies with the face, head and chest, which are more sensitive to temperature changes than the rest of the body.

It just feels as if we are preventing heat loss by covering them up.

If the test group had been just wearing swimming trunks, they would still have only lost 10% of their body heat through their heads, claim the researchers.

Not content with demolishing the above medical folk fact, Ms Vreeman and Mr Carroll pursued several other commonplace beliefs to see if any scientific evidence backed them up.

One popular favourite unsupported by science is the link between children’s increased sugar intake and hyperactivity. Sugar, it appears, does not make children hyperactive.

Around a dozen reputable studies have tackled the link between youngsters’ behaviour and their sugar intake, but none found any difference between children who consumed a great deal and those who did not. It is practically all a figment of parents’ imaginations.

Interestingly, the researchers say, “when parents think their children have been given a drink containing sugar, even if it is really sugar-free, they rate their children’s behaviour as more hyperactive.”

Likewise, the warning that night-time snacking can make you fat is not based on fact.

There was a suggestion that obese women tended to eat later in the day than slimmer women, but the BMJ article notes a fundamental issue.

“The obese women were not just night eaters, but they were eating more meals, and taking in more calories makes you gain weight regardless of when calories are consumed.” So the obese women weren’t eating later, they were starting earlier and eating longer.

And, if you’re wondering about any Yuletide hangover cures, the BMJ researchers say their is “no evidence” to support the effectiveness of artichoke, aspirin, banana, fructose, glucose, prickly pear, Vegemite, or drugs tropisetron and tolfenamic acid.

The only way to avoid a hangover is to consume alcohol in moderation, or not at all.”

Sorry, but happy Christmas anyway.

peter.elson