By Stephen Pincock
Monday, April 02, 2007
Every afternoon, just after lunch, my almost two-year-old daughter takes a nap. Sometimes the task of settling her falls to me, and often as I put her down amid the teddies, snuggled in a pink gingham sleep suit, I feel a sharp twinge of envy.
Who doesn't crave a midday snooze now and then? There are some people, myself among them, for whom lying down somewhere quiet is a necessity.
So I was fascinated to read a few weeks ago that the French health minister, Xavier Bertrand, has called for the country's employers to take seriously the idea of letting their workers take siestas. “Sleep must not be trivialised,” he said. “Why not a siesta at work? It can't be a taboo subject.”
He'll get no argument from me, if only because the scientific evidence is on his side. Many of his countrymen and women will probably agree, too. Reportedly, more than half of French people who suffer poor sleep think it affects their performance at work.
Bertrand's idea is to conduct an experiment in which a limited number of volunteer companies introduce the after-lunch kip, and then study the results. The siesta would be limited to 15 minutes, and if it improves concentration and quality of work it might be adopted more widely.
As it happens, there is already a reasonable amount of evidence that midday sleeps can help with skills such as memory and learning. In 2000, for example, Masaya Takahashi and Heihachiro Arito from Japan's National Institute of Industrial Health studied the effects of a 15-minute nap after lunch on alertness and logical reasoning in 12 students who'd only been allowed four hour's sleep the night before.
They found that the students who had a nap did better in a test of cognitive than their napless counterparts. They also reported less sleepiness and were better at logical reasoning. The benefits were seen particularly in the mid-afternoon, the scientists said - at a time when many of us can be found rifling through desk drawers looking for matchsticks to prop open our eyelids.
Other scientists have looked at naps from the perspective of learning and memory. Sara Mednick and her colleagues at Harvard, for example, have done a lot of work with a test that measures how well people can detect specific images amid visual distractions.
In one experiment, they trained roughly 70 participants to do the visual test early one morning. In the early afternoon, some were told to have a 60-minute nap, others were given a 90-minute nap and a third group of unfortunates weren't allowed any nap at all.
Later that evening all the participants were tested on their ability to perform the test. The no-nap group did significantly worse than they had in the morning, the short-nap group did roughly as well as they had previously and the long-nap group did much better. These findings show that napping helped the learning process.
The results I've described so far are all good reasons for taking naps, certainly, but there are better ones: namely, that napping might also be good for your heart. The evidence for this ultimate slacker's excuse was published this month in the excellent journal Archives of Internal Medicine.
In that study, Androniki Naska from the University of Athens Medical School in Greece studied some 23,000 men and women between the ages of 20 and 86, aiming to discover whether napping had any impact on risk of death from heart disease.
None of the patients in the six-year study had any history of heart disease before the study began. The scientists asked them all if they took midday naps, and if so, how often and for how long. They also reported their level of physical activity and dietary habits over the previous year.
Overall, 792 participants died in the six years of the study, including 133 who died from heart disease. The researchers carefully took account of other cardiovascular risk factors and found that people who took naps of any frequency and duration had a 34 per cent lower risk of dying from heart disease than those who did not. What's more, nappers who took a siesta for 30 minutes or more at least three times a week had a 37 per cent lower risk of heart-related death.
Among working men, the impact was even more substantial. On average, those who took midday naps had a 64 per cent lower risk of death from heart disease during the study than those who did not nap, the researchers found.
Given that I'm a working man (of sorts anyway), this is compelling stuff. All I need to decide now is how long I should be napping for. My daughter manages about three hours a day. Would that be too long, do you think?
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