In a study of 54 adults with sleep disturbances and mild cognitive impairment (MCI), two hallmarks of early dementia, participants taking at least 5,000 IU of vitamin D daily showed better cognitive function than those who didn’t.

The study, recently published in Sleep Medicine, found that participants who reported taking 5,000 IU or more of vitamin D daily scored more than 13% higher on the Montreal Cognitive Assessment (MoCA) than those who didn’t, even after accounting for other factors. A screening tool to detect the risk of developing dementia, MoCA is widely used to assess memory and thinking skills. In this study, lower daily doses of vitamin D were not associated with higher cognitive scores.