Studies of the effect that makes many of us slumber or feel sleepy during the queen's speech on Christmas Day have revealed that changes may be required in Britain's drink drive legislation.

Dr. James Horne, director of the Sleep Research Laboratory at Lough Borough Universities, is investigating post-lunch sleepiness. "We humans are designed to sleep twice a day, once at night and a short nap after lunch, but in this part of the world we tend to repress that." It is a remnant of the same primeval programming that makes all animals in the bush rest in the hot afternoon sun to conserve energy.

In his studies Dr. Horne has been investigating the role of alcohol. The theory is that if you are sleepy after lunch then it figures that alcohol will be more potent after lunch. One would figure then that a pint of beer at lunchtime has more effect than in the evening, when people are more alert. Indeed, we find that it has about twice the effect. "This has more sinister implications. If people take alcohol up to the legal driving limit, their performance is seriously impaired after lunch," he said. "It seems that alcohol interacts with the circadian rhythm of sleep to cause afternoon sleepiness, so that one pint at lunchtime is equivalent, in effect, to a quart in the evening." Dr. Horne recommends mild exercise, a splash of cold air or cold water on the face, or a cup of coffee. Otherwise, take a cat nap. But this should be less than 15 minutes, "otherwise, sleep really sets in and one can wake up feeling very groggy and far sleepier than to be gained with."