High-dose Vitamin D Supplementation and Improvement in Cognitive Abilities, Insomnia, and Daytime Sleepiness in Adolescent Girls.

INTRODUCTION: Vitamin D may affect the modulation of signaling pathways in the central nervous system. We aimed to evaluate the effect of high-dose vitamin D supplementation on neuropsychological functions in female adolescents. METHODS: We studied the effects of 9 weeks of vitamin D supplementation (50000 IU vitamin D3 [cholecalciferol]/week) on cognitive abilities and sleep disorders in 940 adolescent girls. RESULTS: Oral vitamin D supplementation improved cognitive abilities, including memory, inhibitory control, selective attention, decision making, planning, sustained attention, and cognitive flexibility in healthy adolescent girls (P<0.001). The prevalence of subjects with insomnia after intervention fell from 15.0% to 11.3%. Similar results were also found for the prevalence of sleepiness (15.6% reduced to 14.7%), or cases with both insomnia and sleepiness (8.0% reduced to 6.1%; P<0.05). CONCLUSION: High dose of vitamin D can improve cognitive abilities and alleviate insomnia and daytime sleepiness in adolescent girls. Further investigations are required on different population groups (age and gender) to determine the sustainability of these effects. The value of vitamin D therapy in other neurological disorders would also be of research interest.