Sleeping less than six hours a night skews activity of hundreds of genes

Genes affected by lack of sleep include those governing the immune system, metabolism and the body's response to stress

Getting too little sleep for several nights in a row disrupts hundreds of genes that are essential for good health, including those linked to stress and fighting disease.

Tests on people who slept less than six hours a night for a week revealed substantial changes in the activity of genes that govern the immune system, metabolism, sleep and wake cycles, and the body's response to stress, suggesting that poor sleep could have a broad impact on long-term wellbeing.

The changes, which affected more than 700 genes, may shed light on the biological mechanisms that raise the risk of a host of ailments, including heart disease, diabetes, obesity, stress and depression, in people who get too little sleep.

"The surprise for us was that a relatively modest difference in sleep duration leads to these kinds of changes," said Professor Derk-Jan Dijk, director of the Surrey Sleep Research Centre at Surrey University, who led the study. "It's an indication that sleep disruption or sleep restriction is doing more than just making you tired."

Previous studies have suggested that people who sleep less than five hours a night have a 15% greater risk of death from all causes than people of the same age who get a good night's sleep. In one survey of workers in Britain more than 5% claimed to sleep no more than five hours a night. Another survey published in the US in 2010 found that nearly 30% of people claimed to sleep no more than six hours a night.

Professor Dijk's team asked 14 men and 12 women, all healthy and aged between 23 and 31 years, to live under laboratory conditions at the sleep centre for 12 days. Each volunteer visited the centre on two separate occasions. During one visit, they spent 10 hours a night in bed for a week. In the other, they were allowed only six hours in bed a night. At the end of each week, they were kept awake for a day and night, or around 39 to 41 hours.

Using EEG (electroencephalography) sensors, the scientists found that those on the 10 hours-per-night week slept around 8.5 hours a night, while those limited to six hours in bed each night got on average 5 hours and 42 minutes of sleep.

The time spent asleep had a huge effect on the activity of genes, picked up from blood tests on the volunteers, according to a report in the US journal Proceedings of the National Academy of Sciences. Among the sleep-deprived, the activity of 444 genes was suppressed, while 267 genes were more active than in those who slept for longer.

Changes to genes that control metabolism might trigger or exacerbate conditions such as diabetes or obesity, while disruption to other genes, such as those that govern the body's inflammatory response, might have an impact on heart disease. Further genes that were affected have been linked to stress and ageing.

Sleep loss also had a dramatic effect on genes that govern the body's biological clock, suggesting that poor sleep might trigger a vicious cycle of worsening sleep disruption. The tests showed that people who slept for 8.5 hours a night had around 1,855 genes whose activity rose and fell over a 24-hour cycle. But in the sleep deprived, nearly 400 of these stopped cycling completely. The remainder rose and fell in keeping with the biological clock, but over a much smaller range.

"There is a feedback between what you do to your sleep and how that affects your circadian clock, and that is going to be very important in future investigations," said Dijk.

The researchers did not check how long it took for genes to return to their normal levels of activity in the sleep-deprived volunteers, but they hope to in further studies. Though scores of genes were disrupted in the sleep-deprived, the scientists cannot say whether those changes are a harmless short-term response to poor sleep, a sign of the body adapting to sleep-deprivation, or are potentially harmful to health.

Jim Horne, professor of psychophysiology at Loughborough University's Sleep Research Centre, said: "The potential perils of 'sleep debt' in today's society and the need for 'eight hours of sleep a night' are often overplayed and can cause undue worry. Although this important study seems to support this concern, the participants had their sleep suddenly restricted to an unusually low level, which must have been somewhat stressful.

"We must be careful not to generalise such findings to, say, habitual six-hour sleepers who are happy with their sleep. Besides, sleep can adapt to some change, and should also be judged on its quality, not simply on its total amount."

Contributor

Ian Sample, science correspondent

The GuardianTramp

Related Content

Article image
Britain ponders 'three-person embryos' to combat genetic diseases
If given green light, British scientists would be the first to offer treatments letting babies be born with DNA from three people

Ian Sample, science correspondent

20, Mar, 2013 @3:39 PM

Article image
IVF baby born using revolutionary genetic-screening process
Next-generation sequencing could enable IVF clinics to determine the chances of children developing diseases

Ian Sample science correspondent

07, Jul, 2013 @10:15 PM

Genetic map of cancer reveals trails of mutation that lead to disease

Map shows how 20 patterns of mutation drive 30 cancer types, pointing the way to prevention and treatment strategies

Ian Sample, science correspondent

14, Aug, 2013 @5:00 PM

Article image
Genomes project publishes inventory of human genetic variation
DNA sequences made freely available by the 1,000 Genomes Project will be used to uncover the genetic roots of disease

Alok Jha, science correspondent

31, Oct, 2012 @6:00 PM

Article image
Down's syndrome cells 'fixed' in first step towards chromosome therapy

Researchers shut down the extra chromosome responsible for Down's syndrome, paving the way for future treatments

Ian Sample, science correspondent

17, Jul, 2013 @5:00 PM

Article image
Older fathers pass on more genetic mutations, study shows

According to scientists, rates of conditions such as autism and schizophrenia could be a result of the rising age of fatherhood

Alok Jha, science correspondent

22, Aug, 2012 @5:52 PM

Article image
'Three-parent babies' cure for illness raises ethical fear

Mitochondrial disease, passed from mother to child, is incurable. Scientists see a way to eliminate it using donor DNA but this has set off a debate about 'three-parent babies'

Ian Sample, science correspondent

05, Jun, 2012 @2:51 PM

Article image
Waking up to the link between a faulty body clock and mental illness | Prof Russell Foster

Russell Foster: Biological clocks are known to schedule sleep and changes in alertness, mood, strength and blood pressure, but recent studies suggest they are also deeply involved in mental health

Russell Foster

22, Jul, 2013 @6:00 AM

Article image
Night shift work linked to obesity in new sleep study
Research finds employees who sleep during day burn fewer calories than when sleeping at night

Richard Gray

17, Nov, 2014 @8:01 PM

Article image
Masculine faces appeal most to women in countries where disease is rife

A country's health influences women's preference for masculine or feminine-looking faces, claim psychologists

Ian Sample, science correspondent

17, Mar, 2010 @12:05 AM