Boosting circadian rhythms with lighting: A model driven approach

We describe a model-based strategy for defining an optimal lighting schedule for strengthening the circadian rhythms of patients in intensive care units as a means of reducing delirium rates in hospitals. The effect of different lighting schedules on the amplitude of the circadian rhythms was assessed via computer simulations using a model of the circadian system. The simulation results show a large boost of the amplitude of circadian rhythms when the photoperiod is within the 6 h–16 h duration range at relatively modest light levels. It is concluded that a fast recovery of endogenous circadian rhythm can be supported by daily light pulses of about 6 h without necessarily causing visual discomfort to subjects.