Serum Nutritional Biomarkers and Their Associations with Sleep among US Adults in Recent National Surveys

BACKGROUND The associations between nutritional biomarkers and measures of sleep quantity and quality remain unclear. METHODS Cross-sectional data from the National Health and Nutrition Examination Surveys (NHANES) 2005-2006 were used. We selected 2,459 adults aged 20-85, with complete data on key variables. Five sleep measures were constructed as primary outcomes: (A) Sleep duration; (B) Sleep disorder; (C) Three factors obtained from factor analysis of 15 items and labeled as "Poor sleep-related daytime dysfunction" (Factor 1), "Sleepiness" (Factor 2) and "Sleep disturbance" (Factor 3). Main exposures were serum concentrations of key nutrients, namely retinol, retinyl esters, carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lutein+zeaxanthin, lycopene), folate, vitamin B-12, total homocysteine (tHcy), vitamin C, 25-hydroxyvitamin D (25(OH)D) and vitamin E. Main analyses consisted of multiple linear, logistic and multinomial logit models. RESULTS Among key findings, independent inverse associations were found between serum vitamin B-12 and sleep duration, 25(OH)D and sleepiness (as well as insomnia), and between folate and sleep disturbance. Serum total carotenoids concentration was linked to higher odds of short sleep duration (i.e. 5-6 h per night) compared to normal sleep duration (7-8 h per night). CONCLUSIONS A few of the selected serum nutritional biomarkers were associated with sleep quantity and quality. Longitudinal studies are needed to ascertain temporality and assess putative causal relationships.