Date:
August 23, 2026mpairment and sleep problems who took at least 5,000 IU of vitamin D daily scored more than 13% higher on a cognitive test than those taking none. The preliminary findings suggest vitamin D could be worth studying as a potentially modifiable factor during an early window of cognitive decline.
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More than 7 million Americans are currently living with Alzheimer’s dementia, and that number is expected to climb to nearly 13 million by 2050. New research from Emory University suggests that higher vitamin D supplement intake may be linked to stronger cognitive performance in adults who face an increased risk of developing dementia.
The study included 54 adults with sleep disturbances and mild cognitive impairments (MCI), both of which can be associated with the early stages of dementia. Participants who reported taking at least 5,000 IU of vitamin D each day performed better on measures of cognitive function than those who did not take vitamin D.
Higher Vitamin D Intake Linked to Better Cognitive Scores
The findings, recently published in Sleep Medicine, showed that people taking 5,000 IU or more of vitamin D daily scored more than 13% higher on the Montreal Cognitive Assessment (MoCA) compared with participants who took none, even after researchers adjusted for other factors.
MoCA is a widely used screening test designed to assess memory, thinking skills, and the risk of developing dementia. In contrast to the results seen with the higher intake group, lower daily doses of vitamin D were not associated with improved cognitive scores.
The researchers also highlighted the potential importance of when an intervention takes place. MCI is an intermediate stage between normal cognitive aging and dementia.
“In older adults experiencing both sleep disturbance and mild cognitive impairment, this may represent a critical window for intervention, when cognitive changes are emerging, but opportunities to support brain health may remain,” says Victoria Pak, senior author of the study.
“Identifying accessible and modifiable factors, such as vitamin D supplement intake, during the earlier stages of cognitive decline may become increasingly important, particularly as rates of Alzheimer’s disease continue to rise,” adds Pak, associate professor at Emory University’s Nell Hodgson Woodruff School of Nursing.
Vitamin D2 and D3 Showed Similar Results
The researchers also examined whether the form of vitamin D made a difference. Cognitive performance was similar among people taking vitamin D2, which is typically obtained from <a href="https://health.kporia.com/10-best-medicinal-plants-and-their-benefits-to-our-body/” title=”10 Best Medicinal Plants and Their Benefits To Our Body”>plants or fungi, and vitamin D3, which the body produces after sun exposure and which can also come from animal-based foods.
Vitamin D is an essential nutrient involved in muscle and nerve function, and it also plays a role in sleep quality and sleep-wake cycles. Sleep problems are common among people with Alzheimer’s disease. 50% of those with moderate to severe Alzheimer’s disease report sleep disturbances, pointing to a two-way relationship between poor sleep and cognitive decline.
Sleep Problems and Early Cognitive Decline
Vitamin D deficiency has previously been associated with sleep problems including insomnia and more frequent nighttime awakenings. This preliminary study is the first to examine how vitamin D supplement intake relates to cognitive function specifically in a high-risk group experiencing both MCI and sleep disturbances.
The study was funded by the National Institute on Aging of the National Institutes of Health, R01AG097853-01 and R61AG080606.
Other Emory co-authors also include Sirui Zhou, Paul Sudeshna, Lynn Marie Trotti, and Donald Bliwise.
Materials provided by Emory University. Note: Content may be edited for style and length.
- Sirui Zhou, Paul Sudeshna, Lynn Marie Trotti, Donald Bliwise, Victoria Pak. Vitamin D supplement intake is associated with better cognition in persons with sleep disturbance and mild cognitive impairment. Sleep Medicine, 2026; 146: 108960 DOI: 10.1016/j.sleep.2026.108960
Emory University. “This common vitamin was linked to 13% better cognitive scores.” ScienceDaily. ScienceDaily, 23 August 2026. <www.sciencedaily.com/releases/2026/08/260822015138.htm>.
Emory University. (2026, August 23). This common vitamin was linked to 13% better cognitive scores. ScienceDaily. Retrieved September 6, 2026 from www.sciencedaily.com/releases/2026/08/260822015138.htm
Emory University. “This common vitamin was linked to 13% better cognitive scores.” ScienceDaily. www.sciencedaily.com/releases/2026/08/260822015138.htm (accessed September 6, 2026).
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