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 (alpha-carotene, beta-carotene, beta-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.