As we age, changes in the brain can affect memory and other cognitive abilities. Now, a new study has found promising evidence about the potential role of a specific vitamin in supporting cognitive function. Researchers from Emory University examined whether vitamin D supplement intake was associated with cognitive function in people with mild cognitive impairment (MCI) and disrupted sleep. The findings were published in the journal Sleep Medicine. The study focused on 54 adults with diagnosed or suspected MCI who also reported sleep problems. MCI is a condition involving changes in memory and other thinking abilities that are greater than expected with normal aging but do not necessarily interfere significantly with daily activities. Participants completed the Montreal Cognitive Assessment (MoCA), a screening tool commonly used to evaluate cognitive abilities. They also reported whether they took vitamin D supplements and, if so, the type and daily amount. What the researchers found about vitamin D and cognition Participants who reported taking 5,000 IU or more of vitamin D per day had higher MoCA scores than those who did not take vitamin D supplements. The association remained after researchers adjusted for factors including age, sex, body mass index, vitamin D type and education. The researchers also found that the results did not significantly differ between people taking vitamin D2 and those taking vitamin D3. Lower doses of vitamin D were not significantly associated with differences in overall MoCA scores. The study’s authors described the findings as an indication that higher daily vitamin D intake may be associated with better cognition in people experiencing both sleep disturbances and mild cognitive impairment. They said this population may represent an important stage for studying factors that could potentially be modified as cognitive changes emerge. Sleep problems are particularly relevant in this population. The researchers noted that sleep disturbances affect a substantial proportion of people with MCI and that sleep problems and cognitive decline may be interconnected.