Why your chronotype is key to figuring out how much sleep you need

Would we feel better if we slept a bit more? Possibly – but it isn’t guaranteed. While we know the amount of sleep the average person needs, there is a lot of variation. To get a better idea about how many hours you require – and how and when to get it – let’s start with the basics.

According to the US National Sleep Foundation, a typical adult needs between 7 and 9 hours per night, although we begin life needing a lot more – newborns sleep 14 to 17 hours, and this gradually decreases through childhood. Teenagers need about 9 hours a night and people over 65 tend to need around 7 to 8 hours. Sex can also be a factor. “There are some studies that show women, on average, need about 20 minutes more than men do,” says Veena Kumari at Brunel University of London. And there is evidence that humans, just like many animals, tend to sleep a little longer during winter, too.

Of course, there are exceptions. A rare genetic trait called familial natural short sleep sees individuals habitually going to bed late and waking up early, thriving on just 4 to 6 hours. “We don’t know how prevalent this is,” says Liza Ashbrook at the University of California San Francisco, who has identified a number of gene variants involved in the trait, but “it’s a minority”.

Most of us aren’t that lucky, although the occasional disturbed or shortened night doesn’t matter too much. “We are able to get through a night with no sleep and more or less…