Fig. 1

An illustration of the intervention light sequence. The light changed gradually across 30 min between each condition. Each nursing home could choose if they wanted to turn the lights off or to maintain 100 lx and 2500 K throughout the night (21:00–07:00). The patients generally did not spend time in the common room during the night, and whether or not the light was on in the common room depended on the needs of the staff during the night