Do you thrive on three hours sleep? You might have 'short sleeper syndrome', scientists say

Daily Mail​

23-05-2025

We're all regularly told of the benefits of getting at least seven hours of sleep a night.
But a new study has revealed that a small group of people can thrive on as little as three hours of slumber.
While the rest of us would likely nod off at our desks, or start snoring on the train, they appear bright-eyed and bushy tailed.
Now, experts have pinpointed a new genetic variant linked to 'short sleeper syndrome'.
And it could help to develop treatments for sleep disorders such as insomnia and sleep apnoea.
So, are you one of the lucky few who can flourish on just a few hours of kip?
'Our bodies continue to work when we go to bed, detoxifying themselves and repairing damage,' co-author Ying-Hui Fu, a neuroscientist at the University of California in San Francisco, told Nature.
'These people, all these functions our bodies are doing while we are sleeping, they can just perform at a higher level than we can.'
Since the turn of the millennium Professor Fu and her team have been analysing the genes of short sleepers – people who can get by on six hours or less per night.
So far they have identified five mutations in four genes that can contribute to the trait.
This includes in one gene that helps to regulate circadian rhythm – the internal clock responsible for regulating our sleep-wake cycle.
A part of the latest study, the researchers searched for new mutations in the DNA of a naturally short sleeper who slept an average of 6.3 hours per night.
They discovered one in SIK3, a gene that produces a particular type of protein which sends chemical signals to other proteins to change their function.
Mice engineered with the same genetic mutation also slept less, the researchers found – though not by much.
These animals typically snooze for around 12 hours a day, and those with the genetic mutation slept for around 31 minutes less.
The researchers found that the genetic mutation might shorten sleep by supporting the brain's ability to regulate itself and maintain a stable environment.
WHAT IS 'SHORT SLEEPER SYNDROME'?
Short Sleeper Syndrome (SSS), or Familial Natural Short Sleep (FNSS), is a condition where individuals can function normally with less sleep than most people, typically between four and six hours per night.
However, some can thrive on as little as three hours of slumber every day.
They often wake up feeling refreshed and alert, without needing to nap or sleep longer on weekends.
SSS is not considered a sleep disorder, and individuals with SSS don't typically experience negative health consequences from their short sleep duration
Since the mice only lost a fraction of their sleep, it indicates that the SIK3 mutation is not a major cause of reduced sleep needs, Clifford Saper, a neurologist at Harvard Medical School in Boston, Massachusetts, said.
However, it clearly does have some impact.
'This work fits very well with what is known about SIK3, and that may help us understand the basis for sleepiness,' he said.
The researchers hope that finding enough mutations in naturally short sleepers could get a better idea of how sleep is regulated in people, which could lead to treatment for sleep disorders.
Famous faces that didn't get much sleep include Winston Churchill and Margaret Thatcher, who allegedly got by on just four or five hours' slumber. However, for the average person, this is ill-advised.
A 2022 study found that getting less than five hours of shut-eye per night in later life could raise the risk of getting a chronic illness by a fifth.
Researchers looked at 7,864 British people, who were asked at the age of 50, 60 and 70 how much sleep they got on an average weeknight.
These people were tracked over 25 years to see if they developed any of a list of 13 common chronic diseases, including type 2 diabetes, coronary heart disease or dementia.
People aged 50 getting five hours of sleep a night or fewer, compared to those sleeping for seven hours, were found 20 per cent more likely to develop one of the 13 illnesses for the first time.
But they also had a higher risk of going on to get two or more of these diseases.
It shows a lack of sleep is not only linked to illness in later life, but to multiple illnesses which people live with at the same time, raising their risk of hospitalisation and disability.
Jo Whitmore, senior cardiac nurse at the British Heart Foundation, which helped to fund the research, said: 'This research adds to a growing body of research that highlights the importance of getting a good night's sleep.'
ABOUT CIRCIDIAN RHYTHMS
Our internal circadian rhythms, or circadian clock, is responsible for waking our bodies up in the morning and ensuring they get a good night's rest.
In a healthy person, cortisol levels peak at around 8am, which wakes us up (in theory), and drop to their lowest at 3am the next day, before rising back to its peak five hours later.
Ideally, this 8am peak will be triggered by exposure to sunlight, if not an alarm. When it does, the adrenal glands and brain will start pumping adrenaline.
By mid-morning, the cortisol levels start dropping, while the adrenaline (for energy) and serotonin (a mood stabilizer) keep pumping.
At midday, metabolism and core body temperature ramp up, getting us hungry and ready to eat.
After noon, cortisol levels start their steady decline. Metabolism slows down and tiredness sets in.
Gradually the serotonin turns into melatonin, which induces sleepiness.
Our blood sugar levels decrease, and at 3am, when we are in the middle of our sleep, cortisol levels hit a 24-hour low.