Environmental factors and risk of delirium in geriatric patients: an observational study.

Nighttime investigations were associated with incident delirium, even after adjusting for age, cognitive impairment and comorbidity. We cannot out rule that the medical condition leading to nighttime investigations is the true delirium-trigger, so geriatric patients must still receive emergency investigations at nighttime. Hospital environment in broad sense may be a target for delirium prevention.