Sleep-related disorders and thyroid gland: Results from the National Health and Nutrition Examination Survey 2007 to 2012 and Mendelian randomization analyses.

Common sleep problems reduce quality of life and increase chronic disease risk. The relationship between sleep-related disorders and thyroid function is unclear. This study examines the relationship between sleep-related disorders and thyroid disease using the National Health and Nutrition Examination Survey (NHANES) data and Mendelian randomization (MR) analysis. Data from NHANES 2007 to 2012 were used to assess the relationship between sleep-related disorders and thyroid function using weighted multivariable-adjusted logistic regression. A two-sample MR study was conducted using genome-wide association study summary statistics, and methods such as inverse variance weighted were used to explore the causal relationship between sleep-related disorders and thyroid disease. Sensitivity analysis ensured robustness. The study included 6919 NHANES participants. Logistic regression analysis revealed higher thyroid-stimulating hormone levels in the long sleep group (P < .0001, β = 0.85, 95% confidence interval [CI]: 0.54, 1.15). Lower free triiodothyronine levels were found in the normal sleep group (P = .0030, β = -0.06, 95% CI: -0.06, 0.00). Total T4 levels were lower in those with sleep disorders (P = .0157, β = -0.11, 95% CI: -0.20, -0.02). Long sleep was positively associated with thyroglobulin antibodies (TGAb) positivity (P = .0288, odds ratio [OR] = 1.81, 95% CI: 1.06, 3.07), while sleep disorders were negatively associated with TGAb positivity (P = .0176, OR = 0.72, 95% CI: 0.56, 0.95). MR analysis indicated a positive association between long sleep and Graves disease risk (P = .0240, OR = 99.98, 95% CI: 1.83, 5453.63), and a negative association between sleep duration and Hashimoto's thyroiditis risk (P = .0294, OR = 0.72, 95% CI: 0.54, 0.97). Sleep duration is associated with thyroid hormone levels and autoimmunity. Long sleep is linked to higher thyroid-stimulating hormone levels, lower free triiodothyronine levels, and increased TGAb positivity risk, while sleep disorders are linked to lower total T4 levels and decreased TGAb positivity risk. MR studies suggest long sleep may increase Graves disease risk, while shorter sleep may decrease Hashimoto's thyroiditis risk.