Short Sleepers and Why They Don’t Need Much Sleep

Most of us feel terrible after a short night. A rare few do not. They wake after four or five hours genuinely refreshed, stay sharp all day and keep it up for life. These are natural short sleepers. They haven’t trained themselves to get by on less. Their bodies are simply wired to need less sleep in the first place. Here’s what’s going on, and how to tell the real thing from ordinary sleep deprivation.

A short sleeper is someone who regularly sleeps far less than the seven or more hours most adults need, yet feels perfectly rested and works, thinks and feels just fine. It often runs in families and shows up early in life. You might see it called short sleep syndrome, or familial natural short sleep, in the research.

Despite the word syndrome, it is not an illness. The American Academy of Sleep Medicine treats being a short sleeper as a natural variation rather than a disorder to be fixed. True short sleepers don’t feel tired, don’t nap to catch up and don’t show the slips in mood, memory and focus that come from going short on sleep. You will often see famous names like Leonardo da Vinci or Margaret Thatcher described as short sleepers, though those stories are historical hearsay and impossible to check.

The short answer is their genes. Over the past 15 years or so, researchers have tracked down a handful of rare gene variants in families of natural short sleepers. The first, found in 2009, is located in the gene DEC2, also known as BHLHE41. A decade later, after a long search, a second turned up in a gene called ADRB1, and more have since been found in genes called NPSR1 and GRM1.

These tiny changes seem to boost the brain’s wake-promoting signals, so carriers stay alert on less sleep and appear to sleep more efficiently. Rather than clocking up the sleep debt that would floor the rest of us, they seem to get everything they need in fewer hours. It is worth a word of caution, though. These variants were found in a small number of families. Sleep length is shaped by many genes simultaneously, and the science is still evolving. There is likely another short-sleep gene at play, too, SIK3, which we look at in our guide to whether four hours of sleep is enough.

Genuine short sleepers are rare. The vast majority of people who run on very little sleep are not short sleepers at all. They are sleep deprived and simply used to it.

The difference shows in how you feel. A true short sleeper wakes naturally without an alarm, feels sharp all day and never has to catch up. A sleep-deprived person leans on alarms and coffee, feels foggy, drops off the moment they sit still and sleeps far longer at the weekend. Sleep scientist Ying-Hui Fu, whose lab found several of these genes, has made the point plainly. Most people who run on less sleep than they need are simply sleep deprived, even if they have stopped noticing it. Some people cope better with sleep loss than others, yet still need a full night to be at their best. Coping with less is a world away from genuinely thriving on less. You can read more in our guide to sleep deprivation.

No, natural short sleep is written into your DNA, so there is no routine or hack that turns you into one. Cut your nights down to five hours through willpower alone, and you won’t become a short sleeper. You’ll just become sleep deprived, with the fog, the low mood and the health risks that come with it. The amount of sleep you need is largely fixed, and for most adults, that means seven hours or more, a figure backed by a major expert consensus. To find your own number, try our guide on how many hours of sleep you need.

For genuine short sleepers, the evidence so far is reassuring. They don’t appear to pay the usual price for short nights, and some research even hints that their genetics could be protective. For everyone else, it’s a different picture.

Large studies link regularly short sleep to weight gain and type 2 diabetes, a higher risk of heart attack and even raised overall mortality. So, unless you are one of the genuine few, those extra waking hours tend to come at a cost. If you often feel you are running on empty, it is worth talking to your GP.