Variabilidade do sono entre dias de semana e finais de semana : associação com índice de massa corporal e condições crônicas em adultos brasileiros

Abstract

In parallel to the increase in chronic conditions such as obesity, diabetes, hypertension, and stroke, the average duration of sleep has been decreasing over the past few decades. Although obesity and metabolic diseases have a multifactorial etiology, irregular sleep patterns (duration, quality, and regularity) have been recognized as risk factors for the rise of these conditions. Evidence from chronobiological research suggests that sleep variability, particulary weekend catch-up sleep (CUS) and social jetlag (SJL), may lead circadian system misalignment, which in turn would increase the risk of excessive weight gain and chronic conditions related to obesity. Therefore, this study aims to investigate the association between variability in sleep duration and timing on weekends with body mass index (BMI) and chronic conditions. The study utilized data from the national SONAR-Brazil survey, which explores chronobiological aspects related to sleep, eating, and nutrition of Brazilian adults. It is a virtual and exploratory research. Participants included 2,140 Brazilians, residing in Brazil, aged between 18 and 65 years, and not pregnant. Ninety participants who worked night shifts or rotational shifts were excluded, resulting in a final sample of 2,050 participants. Recruitment took place between August 2021 and September 2022, and data were collected through Google Forms, consisting of four blocks: characterization, health and lifestyle, sleep characteristics, and eating and sleep schedules. Data analyses were performed using Stata/IC13 statistical software. CUS and SJL were studied as continuous (in hours) and categorical variables (<1 hour, 1–2 hours, >2 hours). Linear and logistic regression analyses were conducted to evaluate the associations between CUS, SJL, BMI, and chronic conditions, adjusted for sex, age, chronotype, physical activity, education, diet quality, and sleep duration. There was a positive association between SJL and CUS with BMI. The effects persisted even after adjusting for weekly sleep duration, showing an increase proportional to the magnitude of sleep variability. Participants with SJL >2 hours had an increase of 2.29 kg/m² in BMI (95% CI: 0.84; 3.74, p: 0.002), 129% higher chances of having chronic conditions (95% CI: 1.16; 4.52, p: 0.01), and 119% higher chances of being overweight (95% CI: 1.20; 3.98, p: 0.01). Individuals with CUS >2 hours had 78% higher chances of being overweight (95% CI: 1.27; 2.50, p: 0.001) and an increase of 1.61 kg/m² in BMI (95% CI: 0.81; 2.40, p <0.001). Even small extensions of sleep on weekends and variations of just 1 hour are associated with higher BMI values and greater chances of being overweight and having chronic conditions. These findings suggest the importance of promoting sleep consistency and regularity in clinical protocols and public health guidelines to prevent and treat obesity and related conditions.