['Bright artificial light improves non-seasonal depression. Preliminary observations suggest that sunlight could share this effect.', 'Length of hospitalization was recorded for a sample of 415 unipolar and 187 bipolar depressed inpatients, assigned to rooms with eastern (E) or western (W) windows.', 'Bipolar inpatients in E rooms (exposed to direct sunlight in the morning) had a mean 3.67-day shorter hospital stay than patients in W rooms. No effect was found in unipolar inpatients.'] Does morning sunlight reduce length of hospitalization in bipolar depression?