Light levels in a modern intensive care unit: Impact of time of year, window directionality, and outdoor light levels.

The intensive care unit (ICU) environment is designed for the care of acutely ill patients, with lighting conditions reflecting the needs of the busy clinical setting. Earlier ICU studies suggested that daytime and nighttime light levels were misaligned with those required for circadian rhythm entrainment, which can impact patient sleep-wake cycles and recovery from critical illness. In this investigation in San Diego, California, a coastal US city with over 260 days of sunshine annually, we performed a detailed evaluation of light levels in a contemporary academic medical-surgical ICU constructed in 2016, which features modern lighting and floor-to-ceiling windows in each of the 24 rooms.