Getting enough sleep and a regular pattern helps prevent dementia

For most people, little sleep one night equals mental fog the next day.

The hours pass heavy and dense, tinted by a filter of unreality.

The brain reacts slowly.

We think worse, we forget things, we have a hard time staying focused.

If the lack of sleep time is severe, a certain confusion invades us, as if the pieces of the day did not quite fit together.

When this lack of occasional sleep becomes something systematic, prolonged over time, a kind of cumulative effect occurs.

Neuroscience has amply demonstrated, with overwhelming evidence, that getting little sleep as a rule—for years or decades—increases the risk of cognitive damage later in life.

More information

Women in Spain sleep worse than men and take more medication to achieve this

There are several studies that support the mental harm of poor sleep.

One published in 2021 by Nature

magazine

concluded that sleeping six hours or less—the sleep duration of almost 8,000 participants was measured at ages 50, 60, and 70—increases the likelihood of suffering from Alzheimer's and other types of dementia by 30%.

Another analysis released that same year, by researchers at Harvard Medical School, showed even more conclusive results: those who sleep less than five hours are twice as likely to develop dementia as those who sleep an average of five hours. seven hours.

Two recent investigations suggest that not only duration matters.

Both agree in pointing out—although from different approaches—that regularity in sleep patterns could also have a notable influence on our cognition.

It does not seem advisable to alternate highly variable sleep times.

Nor is it completely harmless to frequently modify the time slot in which we stay asleep.

Jeffrey Iliff, sleep and health researcher, led one of these two new contributions to a growing field of analysis.

Cross-referencing data from the Seattle Longitudinal Study (USA), which has been collecting psychosocial information from thousands of individuals since 1956, he and his team set out to better understand the link between stability in the amount of sleep (measured over 20 years ) and the subsequent appearance of some type of dementia.

By videoconference, Iliff summarizes his main finding: “It is not the people who progressively reduce their hours of sleep who are at greater risk of cognitive disability, but those who vary the number of hours slept the most.”

People with little sleep during one season who, in other seasons, find their sheets sticking to them.

And then they sleep little again.

And, after months or years, a lot again.

And so on.

Iliff admits that, for now, we can only speculate about the causes of this strong correlation between unstable sleep and cognitive impairment.

“It is possible that variability is, in isolation, a factor to take into account.

But it is also plausible that other factors associated with a higher risk of dementia (chronic illness, apnea, depression...) cause this variability,” he explains.

The second study on sleep patterns and dementia, carried out by Australian and Canadian researchers, focuses on the consistency of schedules.

Going to bed haphazardly (one day at ten at night; another, say, at 3 in the morning), and making this anarchy the rule, causes—research suggests—a significant increase in risk. of later suffering from Alzheimer's or other neurodegenerative ailments.

One of the authors, Matthew Pase, a researcher at Monash University, ventures to point out a reason that, he qualifies, also falls into the realm of mere conjecture.

“Cardiovascular diseases are more common among people with an irregular sleeping pattern.

These pathologies cause the blood supply to the brain to function worse, which perhaps helps to partly explain this long-term cognitive damage,” he points out.

In the dynamics between sleep and cognition, where multiple elements converge in a complex equation, some evidence confirms what common sense already glimpsed.

Others, on the contrary, seem counterintuitive.

A good number of investigations have concluded, for example, that sleeping a lot (over 9-10 hours) also triggers the possibility of experiencing a gradual loss of cognitive faculties.

In 2017, a meta-analysis identified this finding in 10 publications.

Another study of several studies released in 2019 estimated the increased risk of dementia among sleepyheads at 77% compared to those who remain in the optimal range, estimated at about seven or eight hours.

For Mercè Mayos, member of the Spanish Federation of Sleep Medicine Societies, a key concept would be to resolve this apparent paradox: comorbidity.

That is, the presence of two or more pathologies whose symptoms and mechanisms are sometimes difficult to observe separately.

“Of course, it seems nonsense that sleeping a lot is bad on a cognitive level.

The main hypothesis is that there must be confounding factors: depression or other comorbidities that cause these people to sleep more."

The study on sleep schedules in which Pase participated also contains its dose of strangeness.

If sleeping and waking up without a more or less fixed criterion could be compromising our future cognitive capacity, the risk of dementia also increases when rest is governed by scrupulously strict hours.

Someone who sleeps, say, from 11:00 p.m. to 7:00 a.m. with stubborn perseverance, with almost no exceptions, by the clock.

Pasa slips, as a feasible reason and suggestive line of research, another twist, in this case of a relational type: “Perhaps people who are very strict with their sleep schedules have a very limited social life, something that does not precisely favor good cognitive health.”

In fertile ground for exploration, a phenomenon discovered just a decade ago helps us understand why poor sleep (in quantity and quality) undermines our cognition.

“Now we know that one of the main functions of sleep is to cleanse the neurotoxicity that we generate during the day.

If we sleep poorly, substances accumulate that contribute to neurodegeneration,” emphasizes Javier Albares, director of the sleep unit at the Teknon Medical Center (Barcelona) and author of

The science of good sleep

(Planetadelibros).

Knowing the existence of a glymphatic system—a term coined by the Danish Maiken Nedergaard, who conceptualized this mechanism in 2012—has become a beacon that guides the growing literature on sleep and cognitive damage.

“It acts as a network of spleens that eliminates waste from the central nervous system, especially fibrillar proteins closely related to Alzheimer's, frontotemporal dementia or Parkinson's,” Mayo summarizes.

Albares adds that “these brain cleaning processes are especially activated during non-REM phase 3, when deep slow-wave sleep occurs.”

Mayos advocates “placing sleep as a pillar of health at the same level as nutrition or physical activity.”

And he regrets that this field continues to be “the Cinderella of medicine.”

Little consideration that is reflected in our habits and collective imagination: “Socially, sleeping little is trivialized, it is even rewarded by giving it a positive connotation for the sake of supposedly greater productivity.”

Matthew Pase, who worked for years in the United States, attests to how “well-regarded” it is there to get up very early.

Slowly, things begin to change.

Mayos offers as proof an influential article that appeared last October in

The Lancet

calling for sleep to be included “in public health agendas” around the world.

Pass concludes: “We increasingly know more about its importance for good health throughout our lives.

It is time for the message to reach the population.”

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