Association of Vitamin D and B12 Levels with Actigraphic Sleep in Cognitively Unimpaired Middle-Aged and Older Adults.

BACKGROUND: Low vitamin D and B12 levels are linked to low self-reported sleep quality and conditions comorbid with sleep disturbances in older adults. We examined the associations between serum vitamin D and B12 levels with actigraphic sleep indices in middle-aged and older adults. METHODS: We studied 460 participants aged 40 and older [70.9±12.0(sd)years; 52.8% female; 22.2% Black] in the Baltimore Longitudinal Study of Aging. Predictors included total serum vitamin D and B12,sleep outcomes included total sleep time (minutes), sleep efficiency (%), sleep onset latency (minutes), wake after sleep onset (minutes), and average wake bout length (minutes). We examined race and sex as effect modifiers of associations between vitaminsand sleep. RESULTS: Higher vitamin D concentration was associated with longer total sleep time (B = 23.63 minutes, 95% CI: 9.62, 37.64) and shorter wake bout length (B = -0.29 minutes, 95% CI: -0.50, -0.09). Vitamin D deficiency was associated with shorter total sleep time (B=-23.03 minutes, 95% CI: -42.05 -4.01). The associations between vitamin D and sleep were stronger among Black participants. Higher B12 was associated with shorter wake after sleep onset in women but longer wake after sleep onset in men. B12 insufficiency/deficiency was associated with longer total sleep time in men but shorter total sleep time in women. CONCLUSIONS: Higher vitamin D levels are associated with longer and less disturbed sleep in middle-aged and older adults. Future studies are needed to understand if maintaining optimal vitamin D levels improve sleep quality and promote better sleep-associated health outcomes.