The Effects of Natural Daylight on Length of Hospital Stay.

Background and Purpose: While providing medical services, hospitals generate many data about patients. Such medical data could contribute to better treatments once their associations or patterns have been identified. With properly analyzed medical data, traditional knowledge at an individual level could be further extended to broader populations. This comprehensive study was performed to demonstrate the effectiveness of light using medical data accumulated over 15 years.

Methods: Patients who were admitted to the window or door side of a six-bedded room were included. Patients admitted to the emergency room and elderly people aged >80 years were excluded. Patients' length of stay was compared per what bed they were in (excluding middle beds). A multiple regression analysis was performed with patients admitted to the window or door side to determine whether the window affected their hospital stay. In addition, a multiple regression analysis was performed after adjusting for confounders by 1:1 matching between the two groups (ie, age, sex, and admitting department).

Results: Participants were 38 788 patients with a bed near the window and 46 233 patients with a bed near the door. Results revealed that patients' length of stay was shorter for those near the window compared with those near the door, which was also true after group matching (33 921 participants in each group).

Conclusions: Clinical trials that test evidence-based designs of physical environments in wards or hospital rooms are usually difficult to perform. As an alternative strategy, using accumulated electronic medical data, we assessed this key element of hospital design.