Brains do a lot of work while we sleep—far from being a passive behavior, sleep is actually critical to brain health, and as a result, mental and cognitive health. A few new studies in recent weeks underline how important sleep is, and how detrimental lack of sleep can be. And not just chronic lack of sleep, but a single night of lost sleep. While many people may have heard that sleep deprivation can affect things like metabolism and memory, research is also showing that it can strongly affect anxiety, Alzheimer’s risk, and even chronic health at the level of our genes...
Another study built upon the growing consensus that sleep is a big protector against dementia, clearing away the brain gunk that can accumulate and eventually lead to the amyloid-beta plaques associated with Alzheimer’s. But the new study, from Washington University School of Medicine, focused on the protein tau, which forms the “tangles” also seen in Alzheimer’s-affected brains.
The researchers studied both mice and humans, depriving them of sleep in several experiments. In one, mice, who are nocturnal, showed a doubling of tau levels when they were kept awake during their normal daytime slumber. And in humans, kept awake for one whole night, their tau levels rose by 50%. Finally, when the team injected mice with tau, those who were allowed to sleep normally had much less of it four weeks later than mice who were sleep-deprived—in these mice, it had spread notably, and to parts of the brain known to be affected in humans with Alzheimer’s.
“The interesting thing about this study is that it suggests that real-life factors such as sleep might affect how fast the disease spreads through the brain,” said study author David Holtzman in a statement. “We’ve known that sleep problems and Alzheimer’s are associated in part via a different Alzheimer’s protein – amyloid beta – but this study shows that sleep disruption causes the damaging protein tau to increase rapidly and to spread over time.”
He also suggests that sleep is a necessary part of brain maintenance.