#Sleeping #hours #night #belly #grow #study
A study published in the journal SLEEP sounds the alarm: 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 crucial importance of sufficient and regular sleep from an early age to prevent obesity and metabolic diseases.
Very short nights promote the gain of visceral and subcutaneous fat
Researchers followed a large cohort of 1,107 Hispanic and African American adults aged 18 to 81 for 5 years.
They precisely measured their abdominal visceral (VAT) and subcutaneous (SAT) adipose tissue by CT scan at baseline and 5 years later, as well as their usual sleep duration by questionnaire. The results are edifying among those under 40:
“Compared to participants sleeping 6 to 7 hours, those sleeping 5 hours or less per night had significantly greater accumulation of visceral (+13 cm² vs +3 cm²) and subcutaneous (+41 cm² vs +27 cm²) fat on 5 years, after adjustment for age, sex, ethnic origin and initial adiposity. This represents an increase in volume of +32% for visceral fat and +25% for subcutaneous fat over this period.”
The association was significant even after accounting for other risk factors for obesity 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 location that is particularly harmful to metabolic health.
On the other hand, no significant association was observed in those over 40 between sleep duration and changes in abdominal fat. The authors put forward several hypotheses:
“Young adults could be more vulnerable to the metabolic effects of short sleep due to their often intense pace of life, their stress or even their diet. Another explanation would be an effect of wear and tear: a chronic lack of sleep since adolescence or early adulthood could permanently program the metabolism and promote fat storage. Finally, it is possible that lack of sleep has different effects depending on the period of life, with a more marked impact during the years of physiological maturation.
Too much sleep, also a warning signal?
More surprisingly, the study also reveals a link between long nights of 8 hours or more and abdominal fat gain, although to a lesser extent than for very short nights. Among heavy sleepers under 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 average sleepers.
“Long sleep is often associated with other factors such as depression, a sedentary lifestyle, certain medications or health problems which can also influence body composition in a negative way. These results do not mean that too much sleeping makes you gain weight, but that it may be a marker of a deleterious lifestyle or underlying health problem that deserves to be explored. nuance the authors.
However, some direct biological mechanisms could 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.
Too long sleep could be a reflection of poor quality sleep with waking phases and fragmentation which would be harmful to health.
Ethnic minorities, the first to be affected by sleep disorders
A notable finding of the study is the high prevalence of inadequate 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 at greater risk of short or poor quality sleep, particularly due to socioeconomic factors, more frequent night work, an unfavorable environment or even cultural beliefs around sleep. Unfortunately, these are also populations 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.
Integrating the promotion of good sleep hygiene into prevention messages, training health professionals to detect sleep disorders, promoting access to appropriate care in disadvantaged neighborhoods are among the levers to be activated quickly to reduce these health inequalities.
Banking on sleep to stem the obesity epidemic
This study reinforces a body of arguments suggesting a key role of inadequate sleep duration (too short or too long) in the development of abdominal obesity and its complications, particularly in young adults.
Other work has shown that chronic insufficient sleep disrupts satiety and hunger hormones, increases the appetite for fatty and sugary foods, and reduces energy expenditure and insulin sensitivity. It’s a vicious circle, obesity predisposing in turn to lack of sleep (sleep apnea, reflux, discomfort, etc.).
“The observation that the deleterious effects of poor sleep on body fat set in very early in adult life is crucial. This suggests that systematically integrating a sleep component into obesity prevention strategies from childhood and adolescence could 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.” insists Kristen Hairston, lead author.
Experts recommend that young adults get between 7 and 9 hours of sleep per night, at a regular schedule. Promoting good sleep hygiene (limiting screens and stimulants in the evening, creating a calm, dark environment at the right temperature, managing stress through relaxation, etc.) could be a simple and inexpensive public health lever. costly against the obesity epidemic, alongside messages on nutrition and physical activity.
Taking care of your sleep means taking care of your weight and your future metabolic health.
A message to be widely and urgently disseminated to younger generations to reverse the worrying trend towards obesity and diabetes. Sleep education should be an integral part of school programs in the same way as dietary education. What if good sleep became the new health gesture to adopt from a very young age? Future interventional research will have to confirm the effectiveness in the field of such an approach to treat our nights… and our figure!
