On the relation between a green and bright window view and length of hospital stay in affective disorders.
Level 3 - non-randomized controlled study
Retrospective observational cohort study evaluating room environmental characteristics and length of stay
PubMed 35189997 · doi:10.1192/j.eurpsy.2022.9
What was done
Researchers examined medical records of 244 psychiatric inpatients (mean age 41.8 years, SD = 11.8; 59.8% female; length of stay 7–100 days) admitted with affective disorders to a single clinic between May 2013 and October 2018. Room window views were assessed using photographs classified as showing man-made objects versus green trees, as well as calculating the continuous percentage of green pixels. Room brightness was measured directly with a luxmeter. The authors evaluated the relationship between these environmental measures and patient length of stay.
What was found
No significant difference in length of stay was observed for the binary comparison of man-made objects versus green trees. However, when evaluating continuous measures, a suppression effect emerged: both the percentage of green view and room brightness significantly reduced length of stay (numerical effect sizes, confidence intervals, and p-values were not reported in the abstract). The authors noted that the greenest rooms were also the darkest due to ward layout, causing the two variables to suppress each other's effects when not modeled together.
Why it matters
This study extends findings on healing hospital environments into psychiatric settings, indicating that both natural light exposure and green views may help shorten hospital stays for affective disorders.
Limits
This was a retrospective, non-randomized single-clinic study, leaving room for unmeasured confounding such as baseline illness severity, medication regimens, or seasonal admission timing. The abstract does not provide exact effect sizes or test statistics. Furthermore, room brightness and greenness were inherently confounded by building architecture, where high greenness coincided with reduced light.