Is an hour’s sleep before midnight as good as two after? Can a lie-in at the weekend make up for late nights during the week? We separate the fact from the fiction
A siesta is not the same thing as a power nap. Siestas are a cultural norm in certain places (particularly in hot countries) where people take a brief rest after lunch. We can do this because our circadian biology (body clock) has a natural dip in the afternoon and there is a natural lull in our alertness. If we are extremely sleepy during the day then we should stop and take a nap – especially if our jobs require alertness (lorry drivers, for example). A nap of 15-25 minutes avoids getting into deep sleep, but can still renew levels of alertness and restore the brain’s capacity for learning – and even improve mood. However, sleep is not a commodity to be turned off and on as we see fit. Naps don’t replace the need for night-time sleep.