Do no harm: The beginning of the age of healthy hospital lighting

Anyone who has spent several nights in a hospital can appreciate that, while recovering, they are simultaneously undergoing what feels like sleep deprivation torture. There are the machines that go “bing” incessantly. There are also, more insidiously, the lights [1]. The lighting in a typical hospital is a challenge to our bodies’ expectation of bright days and dark nights [2]. Typical hospital lights are highly irregular, too dim in the day, and too bright at night [3, 4]. Though it is not obvious to us, even at relatively low levels, the light we are exposed to in the evening can have a powerful effect on the circadian clock [5], suppress the release of the sleep-promoting hormone melatonin [6, 7], and reduce the amount and depth of our sleep [8, 9]. In this issue, Vethe et al. [10] demonstrate that simply changing the lighting in a hospital setting to more closely track the natural light/dark cycle can have a beneficial impact on sleep and the circadian system.