Effects of short sleep and sleep deprivation on thyroid hormones and indices: a Bayesian multilevel analysis from the ELSA-Brasil cohort.

Short sleep duration and sleep deprivation are increasingly frequent in the population and associated with negative health outcomes. Few longitudinal studies have assessed the influence of sleep parameters on thyroid hormones and related indices. This study aimed to analyze the longitudinal association between short sleep duration and sleep deprivation and thyroid hormones and indices, stratified by sex. This prospective cohort analysis included 9,564 participants (4,649 men and 4,915 women) from the first (2012-2014) and second (2016-2018) follow-up waves of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Individuals using medications for thyroid dysfunction or drugs known to alter thyroid hormone levels were excluded. Data on short sleep duration, sleep deprivation, sociodemographic characteristics, and health-related behaviors were obtained from multidimensional questionnaires. Thyroid hormones were titrated in centrifuged serum samples collected after a 12-hour overnight fast using a third-generation immunoenzymatic assay. Crude and adjusted Bayesian multilevel models stratified by sex were used to estimate coefficients and 95% credibility intervals (95%CrI). In models adjusted for age, race/skin color, educational attainment, excessive alcohol consumption, smoking, level of physical activity, coffee consumption, and menopause (for women), both men and women with short sleep duration showed lower TSH values compared to those with normal sleep duration. Only women with short sleep duration showed lower TSHI and the values (coefficient.: -0.6019; 95%CrI: -0.9072; -0.2894) compared to women with normal sleep duration. Our findings emphasize the importance of adequate sleep duration and of avoiding sleep deprivation whenever possible to ensure homeostatic maintenance of thyroid hormones.