Increased daylight availability reduces length of hospitalisation in depressive patients.

In a retrospective study, hospital stay in two hospitals was compared for depressive patients. The mean amount of accumulated light impinging the patient's area was 86,145 lux/light period in Hospital Universitari Son Dureta and 258,909 lux/light period in Hospital Universitari Son Espases (~300 % increase). The median stay was 14 days (1q-3q 8-19, n = 101) and 11 (1q-3q 6-15, n = 106) days, respectively. The reduction was significant only for the entire group, though not for subgroups (p < 0.007). Although the light received was not individually measured, results point to a significant effect of light in the recovery time of depressive patients. Prospective studies are needed.