Napping for longer than 40 minutes can lead to an earlier death

They can increase the risk of a young death by up to 32 per cent

For years it’s been believed that naps are healthy. If you are tired enough to fall asleep during the day then your body needs to rest. It’s even supposed to make us more productive later in the day. If that doesn’t settle it, Einstein, Churchill and Napoleon all took afternoon naps. But, in a study conducted by Cambridge University, people who nap for more than an hour a day are 32 per cent more likely to die younger.

Short naps are still recommended, but if your afternoon snooze lasts longer than 40 minutes then you could be at risk of other health problems. Napping for longer means that you enter a deep sleep which can unsettle the body’s metabolic cycle, leading to problems such as heart disease.

Despite suggested health risks, a study at NASA found that a 40 minute nap improved the performances of military pilots and astronauts by 34 per cent and their alertness by 100 per cent, so in the short term, longer naps are effective. There is not yet enough evidence to completely put us off taking lengthier naps when they are needed.

It is not necessarily the act of napping itself that causes nappers to die younger. Taking long afternoon naps may be a sign of other health issues that are causing fatigue. 90 minute naps are often recommended if you have underslept and want to feel fully refreshed when you wake up, but this new study suggests that napping for 90 minutes increases the risk of metabolic syndrome- which includes heart disease, obesity and high blood pressure- by up to 50 per cent.

The good news is that naps of 30 minutes or less are still healthy and harmless. Short naps do not allow your body to enter the deep sleep phase so you wake up feeling more energised and alert. Shorter naps could also boost your creativity. Salvador Dali said that the ideal time for a nap is only a quarter of a second, allowing the sleeper balance between dreams and reality and wake up feeling more creative.

Scientists agree that more research needs to be done on the link between naps and early death. Napping is not going to kill you, so you can continue indulging in the beautiful luxury of an afternoon nap, but 20 to 30 minutes is the new optimum time.