High-Dose Vitamin D Linked to Improved Cognition in Adults With Sleep Disturbances and Mild Cognitive Impairment
- With more than 7 million Americans living with Alzheimer's dementia, a figure projected to reach nearly 13 million by 2050, new research from Emory University suggests that higher...
- The study analyzed 54 adults with diagnosed or suspected mild cognitive impairment who also reported concurrent sleep problems.
- The investigation builds on existing medical understanding regarding the relationship between sleep health and brain function.
With more than 7 million Americans living with Alzheimer’s dementia, a figure projected to reach 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 elevated risk of developing dementia. Published in the October 2026 issue of the journal Sleep Medicine, the study investigated adults experiencing sleep disturbances alongside mild cognitive impairment, both of which serve as early hallmarks of dementia.
Vitamin D Intake and Cognitive Scores in At-Risk Adults
The study analyzed 54 adults with diagnosed or suspected mild cognitive impairment who also reported concurrent sleep problems. Participants completed the Montreal Cognitive Assessment, a widely used screening tool designed to evaluate memory and thinking skills. According to the findings, participants who reported taking 5,000 international units (IU) or more of vitamin D daily scored more than 13% higher on the Montreal Cognitive Assessment compared to participants who took no vitamin D supplements. Researchers noted that this positive association remained evident even after adjusting for other influencing factors. However, lower daily doses of vitamin D were not associated with improved cognitive scores in this group. The cognitive performance of participants did not vary based on the specific chemical form of the supplement they consumed. Vitamin D2, which is typically derived from plants or fungi, and vitamin D3, which is produced after sun exposure or obtained from animal-based foods, yielded similar results.
The Intersect of Sleep Disturbances and Cognitive Decline
The investigation builds on existing medical understanding regarding the relationship between sleep health and brain function. Vitamin D is an essential nutrient necessary for proper muscle and nerve function, but it also plays a direct role in regulating sleep quality and sleep-wake cycles. Clinical data shows that 50% of individuals with moderate to severe Alzheimer’s disease experience sleep disturbances, pointing to a bidirectional relationship between sleep deprivation and cognitive decline. While vitamin D deficiencies have previously been linked to sleep disorders such as insomnia and frequent nighttime awakenings, this research marks a step forward in assessing supplement intake specifically within a high-risk population experiencing both mild cognitive impairment and sleep problems.
A Critical Window for Brain Health Interventions
Mild cognitive impairment represents an intermediate stage between normal cognitive aging and dementia. The Emory University researchers emphasize that identifying modifiable factors during this transition period remains vital for long-term health outcomes.
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.
Dr. Victoria Pak, Emory University As rates of Alzheimer’s disease continue to rise, researchers emphasize the importance of identifying accessible interventions during the earlier stages of cognitive decline. The study was funded by the National Institute on Aging of the National Institutes of Health under grant numbers R01AG097853-01 and R61AG080606. Additional co-authors on the research paper include Sirui Zhou, Paul Sudeshna, Lynn Marie Trotti, and Donald Bliwise.