Circadian disruption by light is a key contributor to psychiatric disorders, so in psychiatric hospitals the lighting matters. At the new 40-bed acute psychiatric unit at St. Olavs Hospital in Trondheim, Norway a two 20-bed wards were built, one with blue-depleted lighting in the bedrooms, bathrooms, hallways, and common areas from 06:30 pm until 06:50 am and standard hospital lighting throughout the day, whereas the other ward utilized standard lighting at all times. Volunteers were assigned to 5 days in each ward, in random order

In the ward with blue depleted lighting, melatonin was less suppressed, the timing of the circadian clock was shifted half hour earlier and REM (dreaming sleep) was longer and less fragmented. Although these studies were conducted with healthy volunteers, they indicate the value of introducing blue content modulated circadian lighting as a critical support to health in hospitals

This study was authored by Dr Daniel Vethe, and his colleagues at the Norwegian University of Science and Technology. The articles were published in the journals Sleep and Scientific Reports (Nature).