Manganese and sleep outcomes in US adults: results from the 2017–2020 NHANES

Manganese (Mn) is an essential micronutrient, but inadequate or excess Mn intake can have a detrimental impact on human health. Despite the essentiality, little is known about the relationship between Mn and sleep. The aim of the study was to examine the relationship between blood Mn concentrations and sleep outcomes in US adults. This cross-sectional study used data on blood Mn and sleep from the 2017–2020 National Health and Nutrition Examination Survey (NHANES) (n = 8356, age ≥18 y). Multivariable logistic regression was used to examine associations between quintiles of blood Mn concentrations and subjective sleep outcomes (short sleep duration, late sleep midpoint, trouble sleeping, and obstructive sleep apnea [OSA] symptoms), adjusting for age, gender, body mass index, race/ethnicity, income, smoking, and inflammation-adjusted serum ferritin concentration (iron status), caffeine, and alcohol intake. Gender-stratified models were used due to interactions with gender. The mean (SE) blood Mn concentration was 9.7 (0.1) μg/L in US adults. In men, a non-linear association was noted in the relationship between blood Mn levels and short sleep duration on weekdays and weekends. The third Mn quintile (Q3) group had lower odds of short sleep duration (<7 h) on weekdays (OR=0.6, 95% CI: 0.4–0.9) than the lowest Mn quintile (Q1, reference) after adjusting for covariates in men. The second Mn quintile (Q2) group had lower odds of late sleep midpoint on weekdays than Q1 (OR=0.6, 95% CI: 0.4–0.8). In women, Q2 group had lower odds of OSA symptoms than Q1 (OR: 0.6, 95% CI: 0.4–0.9). No relationship was noted between Mn and trouble sleeping. Gender differences exist in the association between Mn and sleep in adults. Q1 group had the poorest sleep outcomes, including higher odds of short sleep duration (in men), late sleep midpoint (in men), and OSA symptoms (in women).