Higher vitamin D levels are associated with longer and less disturbed sleep in middle-aged and older adults, with associations stronger among Black participants, while B12 associations with sleep differed by sex.
Higher vitamin D concentration was associated with longer total sleep time in middle-aged and older adults.
Higher vitamin D concentration was associated with shorter average wake bout length, indicating less disturbed sleep.
Vitamin D deficiency was associated with shorter total sleep time.
The associations between vitamin D and sleep were stronger among Black participants than in the overall sample.
Higher vitamin B12 was associated with shorter wake after sleep onset in women but longer wake after sleep onset in men.
B12 insufficiency or deficiency was associated with longer total sleep time in men but shorter total sleep time in women.
The study examined five actigraphic sleep outcomes as dependent variables.
This research suggests that having higher levels of vitamin D in the blood is linked to sleeping longer and waking up less during the night among middle-aged and older adults who do not have cognitive impairment. Specifically, people with higher vitamin D levels slept about 23 minutes more per night and had shorter individual wake periods when they did wake up during the night. People classified as vitamin D deficient slept about 23 minutes less per night compared to those with adequate levels. These findings were based on wrist-worn activity monitors (actigraphy) that objectively tracked sleep, rather than relying on participants' own reports of how well they slept. The study also found that the connection between vitamin D and sleep was especially pronounced among Black participants. For vitamin B12, the picture was more complicated: higher B12 was linked to less nighttime waking in women but more nighttime waking in men, and B12 deficiency or insufficiency was associated with longer sleep in men but shorter sleep in women. This suggests that the relationship between B12 and sleep may work differently depending on a person's sex. This research matters because poor sleep in older adults is associated with a range of health problems, and vitamin D and B12 deficiencies are common in this age group. The study involved 460 adults from the Baltimore Longitudinal Study of Aging, with an average age of about 71 years. While these findings show associations rather than cause and effect, the authors note that future studies should investigate whether correcting low vitamin D levels through supplementation or other means could improve sleep quality and related health outcomes.
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Upload Your LabsDie-Fei Chen, Jill A. Rabinowitz, Fan Wu, Zhi-Kui Wei, Yang An, J. Schrack, et al.. (2026). Association of Vitamin D and B12 Levels with Actigraphic Sleep in Cognitively Unimpaired Middle-Aged and Older Adults.. The journals of gerontology. Series A, Biological sciences and medical sciences. https://doi.org/10.1093/gerona/glag212