Sleeping regenerates us and protects the brain. However, as with everything, moderation is the key. In fact, too little sleep and too much sleep are both factors that pave the way for an increased risk of cognitive decline in the elderly. This emerges from a very recent research published a few days ago in the journal Brain by an American team from the Washington University School of Medicine in St. Louis (Lucey et al, Brain, 2021).
Lifestyle and Alzheimer's
We have powerful tools at our disposal to protect our brains from Alzheimer's. In fact, in recent months, several scientific researches have brought to light how some modifiable habits can reduce the risk of dementia. A few days ago we saw that a diet that includes proteins is certainly protective against Alzheimer's. Today we try to investigate the role of sleep on cognitive decline.
Sleep hours and sleep quality affect brain health
Previous research has already known that sleep deprivation can pave the way, in the long run, to a greater risk of cognitive decline. Thanks to today's research we know that it is not only the number of hours that makes the difference but also the quality of sleep. The scientists came to this conclusion by analyzing data relating to life habits and blood and cerebrospinal fluid tests of 100 volunteers, average age 75 years at the start of the study. For 4 and a half years, the study participants slept with a small electroencephalogram to measure brain activity. Not only that, every year the volunteers underwent visits to assess the levels of the distinctive proteins of Alzheimer's. Comparing the number of hours of sleep with cognitive decline resulted in a U-shaped relationship. This means, that cognitive decline is most noticeable in people who sleep too little, less than 5 hours per night, and too much, more than 8 hours per night. Instead, cognitive function is stable in the central zone of the range of hours spent in bed while asleep.
Therefore, the study shows that it is not only the hours of sleep that make the difference, but also the quality of rest. In fact, too many hours of sleep are linked to poor sleep. Therefore, a good quality of sleep and neither too much nor too little sleep represent an additional help to protect the brain from neurodegeneration.