Losing even one night’s sleep increases levels of Tau, abundant proteins in central nervous system neurons that can be considered a marker of senile dementia, particularly Alzheimer’s disease.
This is the discovery made by a team of researchers at the University of Uppsala who published their study on Neurology.
Tau proteins present in neurons usually form “tangles.” When the formation of these tangles exceeds a certain limit, they accumulate in the brain and lead to Alzheimer’s disease. Before the symptoms of the same disease appear, the accumulation can last for decades. Already in the past, studies had shown that Tau levels in cerebral spinal fluid could increase as a result of sleep deprivation.
According to Jonathan Cedernaes, one of the authors of the study, even a single night’s sleep can cause an increase, albeit slight, in the level of tau in the blood. This, in turn, suggests that repeated sleep interruptions or long-term sleep deprivation can therefore have harmful effects in terms of cognitive function and the risk of Alzheimer’s itself.
The researchers carried out studies on 15 healthy men with an average age of 22 years who had reported, before the start of the experiment, to sleep regularly from seven to nine hours a night.
In the first phase, these people observed a rigorous program of meals and physical activity for two days two nights. After this first phase, blood samples were taken and analyzed.
Then the second phase began, during which the same people were given a normal night’s sleep, followed by a night in which they were kept forcibly awake with lights on and various activities. Subsequent blood tests showed a 17% increase in blood tau levels after just one night of sleep deprivation. The researchers also examined four other Alzheimer’s related biomarkers but these were not characterized by any particular changes or increases.
According to Cedernaes himself, this is explained by the fact that when neurons are active, the release of TAU in the brain is higher than when we sleep. That is why after only one night when awake, the amount is increased the next day.
Now further studies are needed to determine whether these increases cause a general increase in tau levels in the brain over the long term or whether these proteins are eliminated in whole or in part somehow after a sleepless night. Further studies should also be carried out on different populations, e.g. female patients or elderly people.