The effect of light on critical illness

Introduction Th e research of this decade has yielded substantial improvements in the delivery of and technology with which to provide care for critically ill intensive care unit (ICU) patients. Garnering less attention from the medical and scientifi c community is the environment in which that care is provided, which remains impersonal, noisy, and over illuminated. Noticeably, the nursing and business literature is replete with studies on the matter [1,2]. Th is discussion will focus on the available evidence regarding associations between the ICU environment, specifi cally light, and patient outcome. Defi nitions of light and the biology, including neural, hormonal, and immunologic mechanisms, by which it aff ects the body will be initially emphasized. An integrative commentary will be presented at the conclusion. Because of constraints, the focus is upon the critically ill patient, recognizing that much of what will be discussed is equally applicable to the healthcare provider.