Delirium is a common, unpleasant and dangerous complication see amongst older people during hospital stays. A recent prospective cohort analysis has sought to assess the possible relationship between delirium and vitamin D deficiency. Adults aged 60 and older by the end of follow‐up in the linked hospital inpatient admissions data were assessed, up to 14 years after baseline (in total, n = 351,320). 3,634 (1.03%) participants had at least one incident hospital‐diagnosed delirium episode. Vitamin D deficiency (<25 nmol/L) predicted a large incidence in delirium (HR = 2.49; 95% CI = 2.24–2.76; P < 0.0001, compared with a serum level >50 nmol/L). Increased risk was not limited to the deficient group: insufficient levels (25–50 nmol/L) were also at increased risk (HR = 1.38; 95% CI = 1.28–1.49; P < 0.0001). The association was independent of calcium levels, hospital‐diagnosed fractures, dementia, and other relevant co-factors. The authors advocate further research to asses if corrective strategies may assist. See the study details here.