Researchers from Sweden have found that one night of no sleep increases levels of the Alzheimer’s disease biomarker tau in healthy young men. The results of the small study are published today (Wednesday 8 January) in the scientific journal Neurology.
The 15 men who took part in the study had an average age of 22 and reported regularly getting seven to nine hours of quality sleep per night. Researchers controlled when the participants ate their meals and were allowed to be active during their stay at the sleep clinic. In one of the experiments the men were allowed to have a good night’s sleep for two nights, but in the other they were kept awake for the whole of the second night.
Scientists took blood samples in the evening and next morning and compared the levels of different molecules known to indicate brain activity, as well as levels of the protein tau. In diseases like Alzheimer’s, tau clumps together inside cells in the brain to form tangles. These tangles are thought to be toxic to cells and therefore cause damage to the brain that leads to the symptoms of dementia.
The researchers found that the men had a 17% increase in tau levels in their blood after a night of sleep deprivation compared to an average 2% increase in tau levels after a night of good sleep. They did not see an increase in the other markers they measured.
The researchers do not know whether the increased levels of tau in the blood are due to increased brain activity form being kept awake, or increased clearance of tau from the brain.
Dr Sara Imarisio, Head of Research at Alzheimer’s Research UK said:
“Studies like this are useful for building our understanding of the way sleep might impact our brain health. This research shows that a bad night sleep causes an increase of the protein tau in the blood but more research will be needed to work out what this means for levels of tau in the brain, and how long the effects last.
“This study included a small number of young men who usually slept well and so we do not know what the results mean for women, people who regularly do not sleep well, or older people. The researchers only compared levels of tau after one night of bad sleep, so it is not clear if these short-term changes are relevant to someone’s risk of developing Alzheimer’s disease.
While this research is in its early stages, we do know that sleep is important for our general health, and there are also steps that people can take to reduce their risk of dementia. Keeping mentally and physically active, maintaining a healthy weight, not smoking, only drinking within recommended guidelines, eating a healthy diet, and keeping blood pressure and cholesterol in check can help to support brain health as we age.
“Anyone who is experiencing sleep problems or who has questions about their sleep medication should speak to their doctor.”