Doctors find out how much sleep is needed to slow aging

Sleep duration matters more than diet, exercise, and even stress levels when it comes to the rate at which the body ages. This conclusion was reached by an international group of researchers from China, who published the results of one of the largest studies of biological age in the journal Nature.

The scientists analyzed data from more than 500,000 people and tried to answer a question that has long concerned gerontologists: which factor has the strongest influence on how quickly our organs age?

Aging was measured not by the passport

Unlike most similar studies, the researchers assessed not the participants' chronological age, but the state of the body at the biological level.

For this, magnetic resonance imaging, blood protein analysis, metabolic markers and other health assessment methods were used. In total, the specialists simultaneously studied the condition of 17 different organs and body systems — from the brain and heart to the liver, pancreas and endocrine system.

The data obtained made it possible to create a kind of map of human body aging and determine which factors are most strongly associated with accelerated organ wear.

Sleep turned out to be the main factor

The result surprised even the researchers themselves.

Of all the measured parameters, sleep duration showed the closest link to the rate of biological aging.

The most favorable range turned out to be 6.4 to 7.8 hours of sleep per day. People who regularly slept within this interval showed the lowest rates of aging in practically all organ systems.

Moreover, the effect proved to be extraordinarily stable: both too little sleep and too much sleep were associated with accelerated aging of the body.

The study authors note that this is not about any one organ. Changes were observed simultaneously in various biological systems, which points to sleep's global effect on the body.

The brain suffers the most

The brain proved to be the most sensitive to sleep disturbances.

In people who regularly fell outside the optimal sleep range, signs of accelerated brain aging were the most pronounced. This was followed by the hormonal system, the cardiovascular system, and the pancreas.

What particularly attracted the scientists' attention was that eleven independent biological clocks of different organs all showed the same direction of change at once. Such synchrony is considered strong evidence that this is not a statistical coincidence, but a single mechanism of aging.

Sleep deprivation turned out to be more dangerous than previously thought

To verify the results, the researchers additionally analyzed data from another 1.4 million people from 27 different international cohorts.

It turned out that both too short and too long sleep are associated with an increased risk of premature death. However, the mechanisms behind these phenomena were different.

To assess causality, the scientists used the method of Mendelian randomization — one of the most reliable tools in modern epidemiology. It makes it possible to evaluate the influence of factors through a person's genetic characteristics, minimizing the impact of lifestyle and social conditions.

The results showed that people with a genetic predisposition to short sleep really do age faster and have a higher risk of early death.

The specialists link this effect to chronic systemic inflammation, which gradually damages tissues and organs throughout the body.

Why oversleeping is also dangerous

At first glance, the results could suggest that the more a person sleeps, the better. However, the data showed the opposite.

People who regularly sleep nine hours or more more often face serious illnesses. According to the data cited in the study, long sleep is associated with a 65% increase in the risk of stroke, a 42% increase in the risk of depression, and a 41% increase in the risk of cardiovascular disease.

However, the researchers emphasize an important nuance: in most cases, long sleep is probably not the cause of these problems.

Rather the opposite — an increased need for sleep may be an early sign of health problems already developing, which the body tries to compensate for with extra rest.

That is why specialists urge people not to view the universal advice to sleep as much as possible as a scientifically grounded recommendation.

A new benchmark in the fight against aging

The study provided further confirmation that sleep is one of the body's key recovery mechanisms.

If many aging factors are difficult to control, sleep duration remains a parameter that a person can change today. That is why scientists consider controlling sleep patterns one of the most accessible strategies for preserving health and longevity.

Although the researchers stress that the optimal amount of sleep may differ from person to person, the data indicate a fairly narrow range in which the body functions most efficiently.

And if the results of the study are confirmed in further research, the familiar question of how many hours you sleep may become one of the most important indicators of a person's health, alongside blood pressure, blood sugar and cholesterol levels.