High-Dose Vitamin D Linked to Higher Cognitive Scores in Older Adults with Sleep Problems
By morganverity // 2026-08-27
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Older adults with mild cognitive impairment and sleep disturbances who took at least 5,000 international units (IU) of vitamin D daily scored more than 13% higher on the Montreal Cognitive Assessment (MoCA) compared to those taking no vitamin D, according to a study published in Sleep Medicine and conducted by researchers at Emory University. The study included 54 participants and was funded by the National Institute on Aging of the National Institutes of Health. The findings were reported August 23, 2026 by Emory University.

Study Details and Key Findings

Researchers adjusted for other factors, and the 13% improvement remained significant, according to the report. The study found that lower doses of vitamin D showed no association with better cognitive scores. The MoCA is a widely used screening test designed to assess memory, thinking skills, and the risk of developing dementia. Senior author Victoria Pak, associate professor at Emory University's Nell Hodgson Woodruff School of Nursing, said the findings may indicate a critical window for intervention when cognitive changes are emerging but opportunities to support brain health may remain. “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,” Pak stated, according to the Emory University report.

Vitamin D Forms and Broader Context

Both vitamin D2 and vitamin D3 were linked to similar cognitive performance, according to the researchers. Vitamin D2 is typically obtained from plants or fungi, while vitamin D3 is produced by the body after sun exposure and can also come from animal-based foods. The study is the first to examine vitamin D supplement intake and cognition specifically in adults with both mild cognitive impairment and sleep disturbances, the authors reported. The researchers noted that sleep problems are common among people with Alzheimer's disease, and that up to 50% of those with moderate to severe Alzheimer's disease report sleep disturbances. More than 7 million Americans are currently living with Alzheimer's dementia, a number expected to climb to nearly 13 million by 2050, according to the Emory University report. Vitamin D deficiency has previously been associated with sleep problems including insomnia and more frequent nighttime awakenings, the study noted. Additional research has linked higher midlife vitamin D levels to reduced tau protein buildup in the brain, a key marker of Alzheimer's disease [1].

Conclusion and Limitations

Pak emphasized that identifying modifiable factors such as vitamin D during early cognitive decline may become increasingly important as Alzheimer's rates rise. “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,” Pak said in the Emory University release. The study is preliminary, and the authors did not claim causation. The research relied on self-reported supplement use, and the sample size of 54 participants was small. Further research with larger sample sizes is needed, according to the report. Other Emory co-authors on the study included Sirui Zhou, Paul Sudeshna, Lynn Marie Trotti, and Donald Bliwise. The study is published in Sleep Medicine, Volume 146, 2026.

References

  1. Evangelyn Rodriguez. "Could Vitamin D Be Your Brain's Best Defense Against Dementia? New Study Reveals Surprising Link". NaturalNews.com. April 18, 2026.
  2. "The sweet saboteur: New research reveals how sugar accelerates cellular aging". NaturalNews.com. January 6, 2026.
  3. "Study: High Sugar Intake Linked to 43% Higher Dementia Risk". NaturalNews.com. April 28, 2026.
  4. "Study Links Struggles with Common Habits to Accelerated Brain Aging". NaturalNews.com. June 14, 2026.

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