Lack of sleep may increase Alzheimer’s risk, study review suggests

Sleep creditors are coming – and they want you to know that you don’t have this forgiveness, no, just a change in expectations of how and when you’re going to pay them. You think of them lying in bed at night. How much will they require? Do I have a bankroll? She falls asleep, only to wake up an hour later, in a cold sweat. It falls asleep, then wakes up, slipping in and out of consciousness until the next morning.

As the vast majority of humans have discovered, after two or three nights of bad sleep, apathy, difficulty concentrating, irritability, mood swings, and drowsiness often follow.

For a long time, it was thought that these effects, accompanied by cognitive impairments such as poor performance on tests of short memory, could be attributed mainly to a substance called adenosine, a neurotransmitter that inhibits electrical impulses from reaching the brain. In fact, frequent spikes of this element are observed in sleep-deprived rats and humans.

However, these levels can be quickly corrected after a few good nights of rest, which has given rise to the scientific consensus that this sleep debt can be forgiven with two or three good nights of sleep – as evidenced by casual expressions such as “putting the sleep in the day”.

But an article recently published in “Trends in Neurosciences” runs counter to this popular concept that sleep is something that can be compensated for. The review, which outlines the past 20 years of research into the long-term neurological effects of sleep deprivation in animals and humans, points to mounting evidence that getting too little sleep can lead to permanent brain damage and an increase in sleep. risk of degenerative diseases such as Alzheimer’s disease.

“It’s a very important material for defining what has to be done in relation to health and sleep science,” said Mary Ellen Wells, an expert at the University of North Carolina who did not contribute to the article.​

It has long been known that intense periods of lack of sleep are bad for your health. For centuries, forced insomnia was used as punishment and torture. In the first experimental study of deprivation, published in 1894 by Russian scientist Maria Manasseina, puppies forced to stay awake with constant stimulation died after five days.

Examining the bodies afterwards, Manasseina observed that “the brain was the favored site of the most serious and irreversible changes, with hemorrhage of blood vessels and the degeneration of fatty membranes. Total lack of sleep is more lethal to animals than total absence of food,” she concluded.

But there are many ways to not get enough sleep: you can go without sleeping for a long time, in what scientists call “acute sleep deprivation” (in 1963, a student managed to stay awake for 264 hours).

May sleep little often, which is the chronic version. You can still lie down and stay awake, with your mind working nonstop, or relax, watching TV all night long. Studies like Manasseina’s were considered extreme to the point that they were irrelevant to humans.

“Research continued, but discontinuously. How can you keep an animal or human awake until it dies?” said Fabian Fernandez, a neuroscientist at the University of Arizona, who did not contribute to the new review.

In the last 20 years, however, animal research on the topic has become more sophisticated, precise and amenable to human application, according to Sigrid Veasey, a neuroscientist at the University of Pennsylvania, and Zachary Zamore, a researcher in Veasey’s lab, authors of the new review.

After reviewing previous studies in mice, many of which were conducted by Veasey herself, the researchers found that when the animals were kept awake for just a few hours more than normal each day, two main parts of the brain were most affected: the brain. coeruleus, which manages sensations of alertness and stimulation, and the hippocampus, which plays an important role in the formation of memories and learning.

These regions, which in humans are essential for the preservation of the experience of consciousness, in animals reduced the production of antioxidants, which protect neurons from unstable molecules constantly produced, like exhaust smoke, by functional cells. At low rates, these molecules can accumulate and attack the brain internally, breaking down proteins, fats and DNA.

“Even under normal circumstances, being awake incurs penalties for the brain; but when that period goes on too long, it puts a strain on the system. At a certain point, though, there’s nothing you can do. If you ask your cells to stay active, 30% more than normal every day, they will end up dying,” Fernandez said.

In the rat brains, sleep deprivation led to the death of neurons within days of the restriction—that is, a much lower threshold for brain damage than initially thought. In addition, it also caused inflammation in the prefrontal cortex and increased levels of tau and beta-amyloid proteins, linked to degenerative diseases such as Alzheimer’s and Parkinson’s in the coeruleus and hippocampus.

After a full year of regular sleep, however, the same mice still had neural damage and brain inflammation — which Veasey and Zamore suggest suggests that the effects are long-lasting, if not permanent.

Despite this, many scientists assure that the new research should not be cause for panic. “It’s possible that sleep deprivation damages the brains of mice, but that doesn’t mean people should be stressed about not getting enough sleep,” said Jerome Siegel, a sleep scientist at the University of California at Los Angeles who did not contribute to the study. review.

Currently, there is no ethical way to measure the degree and type of cellular damage caused by sleep deprivation in the coeruleum and hippocampus of living humans. What there are are longitudinal studies published over the last 15 years that rely on behavioral change and self-reported sleep data to link poor sleep quality with dementia, depression, metabolism problems, cardiovascular disease, poor immune response, and even averages. lower schoolchildren. They are difficult to confirm, but together with the findings of animal models, they may give an idea that there is some kind of long-term relationship between lack of sleep and physical and cognitive impairments.

“Sleep deprivation can damage the brain, and if it also happens to mice and it’s been proven to happen to other species, it’s more than likely to be true for humans as well. Which obviously begs the question: at what point does it starts to cause damage? Looking at all this literature of chronic cases around a week of bad sleep, it really does suggest that there is some kind of injury,” concluded Veasey.