Sleep deprivation can damage your brain – too little sleep linked to Alzheimer’s
Sleep is essential for brain health even in young years, and a sleepless night risks leading to changes in blood, changes that are related to Alzheimer's disease.
For some, it is enough with so-called sleep school, where you get general tips and advice on sleep hygiene and lifestyle changes. It can be about starting exercise, watching diet, keeping regular sleep times, having dark, silent and cool in the bedroom and giving yourself time for wandering around without screens. The blue light fools body and brain into thinking it's day. This inhibits the secretion of the sleep hormone melatonin and makes it difficult for us to fall asleep.
This is what Swedish researchers at Uppsala University find in a new study that has been published in the journal Neurology.
The study covered two parts
The study included 15 healthy, normal-weight men who had a mean age of 22 years. Everyone had indicated that they received seven to nine hours of good quality sleep each night, which was verified even before the participants were included in the study.
The study covered two parts. In each part, participants were observed for two days in a sleep laboratory, with a strict meal and activity schedule. Blood tests took in the evening and then again in the morning. In each part of the study, participants were first allowed to sleep a regular night’s sleep. In one part, they were then kept awake all night, so that in the other part of the study, they were again allowed to sleep as usual. During the part where the participants were kept awake, they got to play games, watch movies, or talk in a bright room.
Tau – a marker for Alzheimer’s disease
The researchers found that one night’s sleep deprivation resulted in levels of rope rising by about 17 percent in participants, while levels rose around two percent when they were allowed to sleep as usual. Tau is a protein found in nerve cells that can form clumps. These accumulate in the brains of individuals with Alzheimer’s disease, often decades before symptoms of the disease can be seen. Previous studies with slightly older individuals have found evidence that insomnia may increase levels of rope in the spinal cord fluid. Trauma to the head can also increase levels of the protein, and this can then be measured in the blood circulation.
– Many of us experience acute or chronic insomnia at some point in our lives, for example, due to traveling, excessive caffeine intake, shift work, or irregular working hours. Our study suggests that acute sleep deprivation can increase blood rope levels, even in young, healthy individuals.
This may indicate that a recurring lack of sleep in the long term could have adverse effects on brain health, says Jonathan Cedernaes, who led the study.
The researchers also looked at the difference for four other biomarkers in the blood that can be linked, among other things, to Alzheimer’s disease and damage to nerve fibers. They found that some of these had a clear circadian rhythm, but none of them were affected by the alertness.
Use is considered harmful
Cedernaes points out that a clear accumulation of rope in the brain is usually considered to be harmful. But today it is not known what higher levels of rope in the blood after sleep deprivation.
– Tau is secreted from nerve cells when they are active, and animal models suggest that chronic such activity can lead to harmful accumulation of tau in the brain.
Higher levels of tau in the blood could mean that tau from nerve cells are more effectively cleared from the brain, or it may reflect generally higher levels of tau in the brain.
More studies are needed to clarify and distinguish such mechanisms, says Jonathan Cedernaes.
Future studies are needed
The main limitation of the study was its size (15 individuals). Also, to have as similar a group as possible, the researchers examined only young men. The results are thus not confidently transferable to what happens in children, women, or older individuals who are exposed to acute insomnia.
– Future studies are also needed to show how long tau levels are elevated in the blood after acute insomnia. More research is necessary to determine whether increased levels of tau in the blood are a marker of an unhealthy mechanism, how the risk of dementia is affected after chronic repeated exposure to shortened, disturbed, or irregular sleep. Longer-term studies can hopefully also give us insight into whether you can try to improve your sleep as early as younger years, to reduce the risk of Alzheimer’s and other dementia diseases, says Jonathan Cedernaes.
The study was conducted together with Christian Benedict at Uppsala University, as well as Henrik Zetterberg and Kaj Blennow, both active at the Sahlgrenska Academy and the University of Gothenburg.