2024-04-26 05:50:14
A a study published in the journal SLEEP the alarm sounds: young adults who sleep less than 5 hours per night are particularly at risk of storing fat in the abdominal area over the years. These results highlight the critical importance of adequate and regular sleep from an early age to prevent obesity and metabolic diseases.
Very short nights promote visceral and subcutaneous fat gain
Researchers followed a large cohort of 1,107 Hispanic and African American adults between the ages of 18 and 81 for 5 years.
They precisely measured their abdominal visceral (VAT) and subcutaneous fat tissue (SAT) by CT scan at baseline and 5 years later, as well as their usual sleep duration according to a questionnaire. The results are increasing among those under 40:
“Compared to participants who slept 6 to 7 hours, significantly more visceral (+13 cm² vs +3 cm²) and subcutaneous fat (+41 cm² vs +27 cm²) accumulated over 5 years in those who slept 5 hours or less per night adjusted for age, sex, ethnicity and baseline adiposity. This equates to an increase of +32% in visceral fat and +25% in subcutaneous fat over this period.”
The association was significant even after accounting for other obesity risk factors such as smoking, physical activity, calorie intake and education level.
Lack of sleep therefore appears to be an independent and powerful risk factor for the accumulation of abdominal fat, a site particularly detrimental to metabolic health.
On the other hand, no significant association was observed for those over 40 years of age between sleep duration and changes in abdominal fat. The authors put forward several hypotheses:
“Young adults may be more vulnerable to the metabolic effects of short sleep because of their often hectic pace of life, their stress or even their diet. Another explanation would be a wear-and-tear effect: chronic sleep deprivation from adolescence or early adulthood may permanently program the metabolism and promote fat storage. Finally, lack of sleep may have different effects depending on the period of life, with a more significant impact during the years of physiological maturation.
Too much sleep, also a warning sign?
Surprisingly, the study also shows that there is a link between long nights of 8 hours or more and abdominal fat gain, although to a lesser extent than very short nights. Among heavy sleepers under the age of 40, the average increase in fat over 5 years reached 6 cm² for the visceral compartment and 20 cm² for the subcutaneous tissue, intermediate values between small and medium diagonals.
“Long sleep is often associated with other factors such as depression, a sedentary lifestyle, certain medications or health problems that can also have a negative impact on body composition. These findings do not mean that too much sleep makes you overweight, but that it could be a sign of an unhealthy lifestyle or an underlying health problem that deserves to be explored. the author’s nuance.
However, some direct biological mechanisms may also come into play. Studies have shown that excessive sleep duration is associated with disturbances in metabolic and hormonal rhythms, a reduction in thermogenesis and energy expenditure.
Sleeping too long could be a sign of poor quality sleep with stages of awakening and fragmentation that could be detrimental to health.
Ethnic minorities, the first to be affected by sleep disorders
A significant finding of the study is the high prevalence of insufficient sleep duration in this ethnic minority cohort. Among those under 40, 30% of Hispanic men and 27% of African-American women reported sleeping less than 5 hours per night. Conversely, more than 50% of Hispanic women slept 8 hours or more.
“Numerous studies have shown that African Americans and Hispanics are more at risk of short or poor quality sleep, especially due to socioeconomic factors, more frequent night work, an unfavorable environment or even cultural beliefs around sleep. Unfortunately, these are also communities at higher risk of obesity and diabetes. Identifying sleep disorders in these groups and implementing appropriate interventions is a major public health issue. » comments Dr Carmen Sanchez, co-author.
Among the levers to be implemented quickly to reduce these health inequalities are the integration of the promotion of good sleep hygiene with prevention messages, the training of health professionals to detect sleep disorders, access to appropriate care in disadvantaged neighborhoods to promote.
Banking on sleep to stop the obesity epidemic
This study reinforces a number of arguments that suggest that insufficient sleep periods (too short or too long) play a central role in the development of abdominal obesity and its complications, especially in young adults.
Other work has shown that chronically insufficient sleep affects satiety and hunger hormones, increases appetite for fatty and sugary foods, and decreases energy expenditure and insulin sensitivity. It is a vicious circle, predisposing obesity after lack of sleep (sleep apnea, reflux, discomfort, etc.).
“The fact that poor sleep affects body fat very early in adulthood is critical. This suggests that the systematic integration of a sleep component into childhood and adolescent obesity prevention strategies may be lifesaving in the long term, particularly in at-risk populations. It is urgent to raise awareness among the general public and health professionals about the issues of good sleep for weight and metabolism.” argues Kristen Hairston, lead author.
Experts recommend that young adults get between 7 and 9 hours of sleep per night, on a regular schedule. Promoting good sleep hygiene (limiting screens and stimuli in the evening, creating a quiet, dark environment at the right temperature, managing stress through rest, etc.) could be a simple and inexpensive public health lever against the obesity epidemic, along with messages on nutrition and physical activity.
Taking care of your sleep means taking care of your future weight and metabolic health.
A message that needs to be disseminated widely and urgently to the younger generation to reverse the worrying trend towards obesity and diabetes. Sleep education should be an integral part of school programs in the same way as nutrition education. What if good sleep became the new sign of health to be accepted from a young age? Future intervention research will have to ensure the effectiveness of such an approach to treating our nights… and our figure!
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