Poor sleep makes you fat

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A recent research shows that a single night of insomnia promotes weight gain by disrupting the metabolism of the adipose tissue and muscles.

In our society, hyperconnected, where there is always something going on 24 hours a day, 7 days a week, more and more people are suffering from a sleep deficit. It is estimated that at least 50 % of the population sleeps insufficiently (less than 7 hours per night) and/or poor-quality sleep, marked by difficulty falling asleep, periods of insomnia or awakenings intermittent.

In addition to the immediate impact of this lack of sleep on the overall functioning of the person who is tired (lack of attention, irritability, loss of productivity), a significant number of studies indicate that poor sleep may also promote the development of a range of serious chronic conditions, from heart disease to certain types of cancers. Sleep is not thus used not only to rest and recover our energy, but represents a period metabolic who carries several important implications for the organization as a whole.

Impacts metabolic

An index of this important role comes from several observations showing that lack of sleep is associated with an increase in the risk of many metabolic disorders, including obesity, the metabolic syndrome (a combination of hypertension, overweight and dyslipidemia) and type 2 diabetes.

The risk of developing these conditions is particularly pronounced in people who have chronic problems with sleep (night workers, for example), but could also be observed in people whose sleep is disrupted for only a few consecutive nights.

According to research on this phenomenon, the lack of sleep promotes overweight causing a rise of hormones that govern appetite, encouraging over-consumption of food, as well as by disrupting the metabolism of sugar. In the latter case, a study showed that young men (18-27 years) who were lack of sleep (only 4 hours in bed for 6 consecutive days) showed a significant decrease (30 %) of insulin secretion in response to glucose, of the same order as that observed normally in individuals aged 60 years and older(1).

To sleep properly is not only necessary to rest, but plays an important role in the maintenance of normal physiological functions.

More fat, less muscle

A recent analysis of biochemical phenomena altered by lack of sleep allows you to visualize at a molecular level the impact of this deficiency on the metabolism(2).

In this study, the researchers have collected from 15 volunteers of samples of blood, fat and muscles on two occasions, either after a night of normal sleep or following a sleepless night. First, they observed that the deficiency of sleep induces important changes in the profile of DNA methylation, an epigenetic modification that plays an important role in the control of gene expression. At the level of adipocytes (cells that store fat), these modifications cause an increase of the activity of genes involved in fat storage, while at the level of the muscles, rather it is a degradation of structural proteins that is observed.

These observations are in agreement with several studies showing that a deficiency of sleep leads to the accumulation of fat mass and decreases in parallel with the muscle mass.

Since these changes are already visible after only one sleepless night, we can imagine how the lack of sleep repetition can adversely affect the metabolism and support the development of many conditions associated to overweight.

(1) Spiegel K et al. Impact of sleep debt on metabolic and endocrine function. Lancet 1999 ; 354 : 1435-1439.

(2) Cedernaes J et al. Acute sleep loss results in tissue-specific alterations in genome-wide DNA methylation state and metabolic fuel utilization in humans. Sci. Adv. 2018; 4: eaar8590.

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