Why Do We Need to Sleep, and What Happens If We Do Not?

Sleeping less than seven hours a day has disastrous effects on health, but what sense does it make that we need to rest a third of our life?

Lack of sleep is no joke. There are no scientific studies with humans for obvious reasons, but we know that a few days of total sleep deprivation are enough for laboratory rats to suffer a frightening end: weakness, skin sores, weight loss (despite eating more than enough) and finally death.

The truth is that in this sleep are not alone, although there are significant differences. Bears and rodents spend months sleeping during hibernation, while dolphins and other marine mammals can spend weeks without sleep. In our case, although it is not known with total security because we sleep, it is clear that we need to rest. Mainly because of our brain.

While we are awake neurons establish connections between them as a result of our experiences. If we have burned ourselves with a hot pan, in our brain, we will associate the concept of the pan with the pain of the burn, creating a memory and an answer that avoids as much as possible that it happens again. This happens millions of times a day.

During sleep, our brain is dedicated to “prune” these connections, eliminating those that are not important, and reinforcing those that are. Dreams seem to be part of the process, a kind of simulator in which different responses are tested, especially emotional, to the acquired experiences. Discoveries indicate that there is also a process of “washing” during the night in which the brain eliminates neurotoxic byproducts that accumulate during waking hours.

In the words of neuroscientist Maiken Nedergaard, from the University of Rochester “ It’s like having a party at home. You can have fun with the guests or clean up, but you can not do both at the same time. “

How much is there to sleep?

You could answer that it depends, but in reality, it is not like that. The amount of sleep recommended for adults is between seven and nine hours a day, but few humans meet it.

Sleeping less than seven hours is not just a problem of fatigue. There are well-studied physical consequences:

  • More body fat: in a study with 496 adults over 13 years it could be seen that those who slept less than six hours were 7.5 times more likely to be overweight, regardless of physical activity levels, demographic factors or family history.

  • Appetite Disorders: Sleep restriction in a controlled study resulted in a significant drop in the hormone leptin (the one that tells you that you have eaten a lot) and an increase in ghrelin (the hormone that makes you hungry). Besides, it was not just any hunger, but cravings for calorie-dense foods, especially sugars.

  • Less muscle mass: any athlete will tell you that muscles are made in bed (and fat is lost in the kitchen, but that’s another matter). During the night increases the secretion of growth hormone, which stimulates the repair of tissues, from the skin to the muscles, through the lungs and nails. Lack of sleep interferes with this process. In a study in which volunteers underwent a diet of weight loss, in two weeks all lost weight, about three kilos, but those who slept 5.5 hours lost less fat and more muscle than those who slept 8 hours. Also, his metabolism decreased, making them more vulnerable to the rebound effect.

  • Diabetes Risk: Insulin sensitivity is your body’s ability to process sugar. When you become insulin resistant, blood glucose stays elevated longer, so more insulin is needed each time to get the same effect. When the system breaks down, you have type 2 diabetes. As expected, it has been proven that a single night of insomnia suffices to reduce the sensitivity to insulin in the liver and other tissues.

  • More stress: lack of sleep affects the hypothalamic-pituitary-adrenal axis, the system that starts with the brain and controls nothing less than metabolism, digestion, the immune system, and above all, stress. In the morning rises cortisol, the stress hormone, to help us wake up, and descends within a few hours. But if the system is disturbed by lack of sleep, cortisol remains high until the afternoon, with all that it takes as a gift: more chances of suffering diseases, more irritability and, closing the circle, less sleep the next night.

  • Less brain: total sleep deprivation has serious long-term effects, such as memory loss, or the creation of false memories. But even a partial deprivation can affect cognitive functions such as working memory, attention and decision making.

  • Less life expectancy: sleeping fewer hours it seems that you have more time to live, but I feel like showering the party because, in reality, you live less. In a review of 17 studies on sleep, those who slept between five and seven hours had a 12% higher mortality. Interestingly, mortality also increased in those who slept more than eight hours.

  • Worst sex: when studying healthy and young men who were made to sleep only 5 hours a day for a week it was found that testosterone had dropped by up to 15 %. On the contrary, for each hour of sleep, the women in a study saw their chances of having sex with their partner increase by 14 %.

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