Unlike their northern counterparts, people in Latin countries have always valued the siesta, that after-lunch snooze that allows time for digestion and avoids having to work at the hottest time of the day. Anglo-Saxon culture tends to look down with disdain on such Mediterranean laziness but it seems the Southerners may have it right.

A series of studies have established that there's a definite value to napping. Scientists at a number of prestigious universites in the US and Australia have researched the effects of different nap times and conclude that it's smart to nap. It can give you a boost that lasts far longer than the nap itself. Here's a chart that shows the effects of different nap lengths:

If you need a quick boost, a 10 to 20-minute power nap will give you most bang for your buck. You'll be more mentally sharp for at least two hours afterwards. Longer naps give a longer benefit, but after 30 minutes of napping you'll tend to be groggy for up to half an hour before the benefits kick in.

A nap of 90 minutes may not go down well in the workplace but it gives the brain time to enter REM sleep, which improves your creativity and helps absorb facts in a learning environment.

One problem is making sure you wake up again. Some people find the solution is to hold a bunch of keys in your hand. When you fall asleep it apparently takes 10 to 15 minutes for you to drop them, then the sound wakes you.

The most important thing is to nap during the day. Leaving it till the evening will interfere with your normal sleep patterns and have you waking up in the middle of the night. And one thing to watch out for is dreaming during a nap of less than 20 minutes; this means you are almost certainly very sleep-deprived.

So maybe the Italians have it right with their 3-hour lunch breaks that enable them to go on working until 7pm, just in time to hit the bars and restaurants.

Now I'll just take a short nap. Wake me up in 20 minutes...