What impact does sleep have on our health?

Studies have shown that quality sleep (between 7 and 9 hours continuous sleep, not time spent in bed) saves our memories and knowledge from the clutches of oblivion.

If you're a student or currently in training, think about it!

As well as enabling a transfer from short-term to long-term memory, sleep also transfers motor memories (fine, specific movements in sport, playing a musical instrument, etc.) to brain circuits operating below the level of our consciousness.

Motor actions that we train ourselves to repeat, such as a particular sport or playing the piano, thus become instinctive habits, coming easily out of the body without seeming to require any particular effort. A good reason to go to bed early after your guitar lesson or Wednesday afternoon soccer practice!

One study found a 60% increase in the activity of the amygdala - a key site in the triggering of strong emotions such as anger or rage, linked to the fight-or-flight response - in terms of emotional reactivity in sleep-deprived participants. MRIs of those who had slept a full night showed instead a modest and controlled degree of reactivity in the amygdala, despite having seen exactly the same images.

Deprived of sleep, we produce disproportionate, inappropriate emotional reactions, and are unable to place events in a general or known context. This is why sleep deprivation is also a determining factor in bullying, violent behavior and behavioral problems in children of all ages. Poor sleep quality is also a determining factor in the relapse rate of many addictive disorders, associated with an extreme need for recognition and a lack of control over the rational social seat that is the prefrontal cortex.

Important preventive information: The impact of sleep deprivation in childhood is significant on drug and alcohol use in adolescence, even when other risk factors such as anxiety, attention deficits or parental drug use are taken into account.

Bad sleep, bad heart!

Take this Japanese study of over 4,000 male workers. Over a 14-year period, those who slept six hours a night or less were 400-500% more likely to suffer cardiac arrest or more than those who slept more than six hours.

As we approach middle age, the impact of sleep deprivation on the cardiovascular system skyrockets.

It has been shown that adults aged 45 or over who sleep less than six hours a night are 200% more likely to have a heart attack than those who sleep seven or eight hours a night.

This discovery shows just how much we need to put sleep first at this age - and unfortunately this is often the time when family or professional circumstances encourage us to do the exact opposite.

High blood pressure is so common today that we forget its sometimes fatal consequences.

As well as speeding up your heart rate and raising your blood pressure, lack of sleep damages the tissue of blood vessels, particularly those that feed the heart itself, the coronary arteries.

These corridors of life must be clean and wide open to supply your heart with blood at all times. If you narrow or block these passages, your heart can suffer an all-out and often fatal attack due to the lack of oxygen in your blood, colloquially known as a "heart attack".

One of the causes of coronary artery blockages is atherosclerosis, when hardened plaques containing calcareous deposits fill up the heart's passageways.

Researchers at the University of Chicago carried out a study on almost 500 healthy middle-aged adults. They analyzed the health of these participants' coronary arteries over several years while assessing their sleep.

Participants who slept only five to six hours a night were 200% to 300% more likely to develop coronary artery calcification after five years than those who slept seven to eight hours or more.

All the more reason to take care of your sleep hygiene!

The less sleep you get, the more likely you are to eat.

What's more, your body becomes unable to effectively manage calories, including blood sugar levels.

For both these reasons, sleeping less than seven hours a night increases your risk of gaining weight, becoming overweight or obese, and developing type 2 diabetes.

Too much blood sugar, or glucose, sustained over several weeks or even years, inflicts damage on your body's tissues and organs, which can worsen your health and shorten your life span.

In a healthy individual, the hormone insulin triggers your body's cells to rapidly absorb glucose from your blood when it increases, as after a meal. Informed by insulin, the cells open special channels on their surface, like efficient pipes on the side of the road during a torrential downpour. They have no trouble managing the deluge of glucose surging through the transit arteries, preventing what would otherwise become a dangerous rise in blood sugar levels.

However, if your cells stop responding to insulin, they can't absorb glucose from your blood. The body then goes into hyperglycemia.

If such a condition persists, and your body's cells remain intolerant to high glucose levels, you enter the pre-diabetic stage, before developing generalized type 2 diabetes.

In a study carried out on several continents by independent researchers, healthy participants were forced to sleep just four hours a night for six nights.

By the end of the week, these previously healthy participants were 40% less efficient at absorbing a standard dose of glucose than when they were rested.

Even though few of us sleep more than four hours a night, to give you an idea of what this represents, consider that if the researchers had shown these results to an uninformed family doctor, the GP would have immediately classified these individuals as pre-diabetic.

Numerous scientific laboratories around the world have concluded that sleep deprivation has an alarming effect, some even in the case of less spectacular sleep reductions.