Inadequate sleep alters the activity of over 700 genes, scientists report. In the research, sleeping less than six hours per night for just one week impacted genes related to metabolism, inflammation and immunity.
Study co-author Professor Colin Smith of the University of Surrey, UK, said the team 'are starting to make breakthroughs that will have an impact on our understanding and treatment of poor health arising from insufficient sleep'.
Previous research links a lack of sleep to obesity, high blood pressure, heart disease and diabetes. Although this study may help explain that link, the scientists do not yet know the health effects - if any - of the gene changes observed.
Participants in the study stayed at the University of Surrey's Sleep Research Centre during the trial, and were assigned to sleep for either six hours or ten hours per night. After one week of this sleep pattern, participants had to stay awake for around 40 hours while blood samples were taken and analysed. Following a break, the same participants were switched to the opposite sleep pattern and their blood tests analysed again.
The scientists looked at levels of RNA in the blood, comparing levels after sufficient sleep to levels after insufficient sleep. RNA levels are used as an indirect measure of gene activity.
In addition to finding significant differences for RNA levels associated with 711 genes whose activity would otherwise be stable, the researchers looked at RNAs with a circadian rhythm; that is those that fluctuate according to the time of day. They found that 374 of the 1,855 genes linked to circadian rhythm stopped fluctuating in people who had been sleep deprived. Again, the implications of this are unclear.
Professor Jim Horne, of Loughborough University's Sleep Research Centre, who was not involved in the study, advised caution in interpreting the results. He told the Guardian: 'The need for eight hours of sleep a night [is] often overplayed and can cause undue worry. Although this important study seems to support this concern, the participants had their sleep suddenly restricted [...] which must have been somewhat stressful'. He suggests those sleeping six hours per night routinely may adapt.
The study, published in the journal Proceedings of the National Academy of Sciences (PNAS), was small, involving only 26 healthy participants, and its wider applicability is as yet unknown.