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After the age of 50, short nights of sleep are associated with a higher risk of chronic diseases, according to a French study.
Sleep is important for health. It regulates the metabolism, promotes better skin elasticity, reduces the risk of depression… and even reduces the risk of multimorbidity (ie having several chronic diseases). This is at least what emerges from a new study, conducted by researchers from Inserm and the University of Paris Cité.
Chronic disease: little sleep would increase the risk by 20%
To reach this conclusion, scientists tried to understand how the duration of sleep “was associated with the progression of chronic diseases during aging“.
To do this, they analyzed data from 7,000 Britons, taken from the Whitehall II study at University College London. The participants had to answer a questionnaire on several occasions (at the age of 50, 60 and 70) relating to their sleep duration.
To supplement this data, a group of 4,000 volunteers wore a connected watch for a week.
The researchers then cross-referenced this data on sleep duration with data on the participants’ health status.
Result: Scientists noticed that there was “a robust association between short sleep duration (less than or equal to 5 hours) at ages 50, 60 and 70 and a higher risk of multimorbidity in the order of 30 to 40% depending on age“.
Another interesting observation: a lack of sleep at the age of 50 increased the risk of developing a first chronic disease by 20%. In participants who were already ill, it also increased the risk of multimorbidity by 20%.
For research teams, these results “could explain the increased risk of death of around 25% observed in people aged 50 with a sleep duration less than or equal to five hours per night.”
Finally, a long night’s sleep (more than 9 hours) could reflect the presence of a chronic disease according to the researchers.
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Why does lack of sleep affect the body?
The development of chronic diseases – such as diabetes, arthritis, asthma or hypertension – could be explained as follows:
“During the night, our brain evacuates the proteins accumulated during the day thanks to the lymphatic system. When the nights are short, this function of “cleaning” of our brain is impaired and over time, these substances accumulate and hinder the function of the brain. It should be noted that many functions of our body follow a 24-hour rhythm and sleep contributes to the regulation of various physiological processes such as the regulation of endocrine, metabolic or inflammatory processes. In the absence of good nights of sleep, these processes are impeded over time and this can promote the occurrence of chronic diseases”, reveals Séverine Sabia, Inserm researcher and first author of the study.
Slide: Sleep: how long should we sleep according to our age?