Fig 3. Circadian medicine in ICUs.

Critically ill patients frequently exhibit disturbed or absent diurnal rhythms. This is likely to be a result of their illness and sedative measures but could also be related to the often-arrhythmic environment of an ICU (inadequate light exposure, parenteral nutrition, etc.). At the same time, they are arguably the best monitored patients, and vast amounts of routine clinical data are available with time courses for a variety of physiological parameters. We propose evaluating this treasure trove of information much more systematically with data science methods to detect the clock and improving light settings in the ICUs to target the clock. The analysis of clinical source data will help to characterize patients in the ICU in terms of their circadian rhythms, to identify predictors of circadian disruption as well as therapy-based improvements, and to associate circadian rhythms with clinical parameters (for example, delirium). In addition, since current ICUs do not provide adequate light settings, we have implemented a novel concept at Charité –Universitätsmedizin Berlin, consisting of a light ceiling for each experimental ICU bed that extends from the head above the patient to the patient’s feet [67]. Each light ceiling consists of multiple layers of light-emitting diodes designed to target the patient’s circadian clock. ICU, intensive care unit. Photos can be used with kind permission of GRAFT; photo credit is given to Tobias Hein.