Sleep and inflammation: a bidirectional relationship

Abstract Sleep and inflammation are bidirectionally linked, and this relationship is assumed to be important for the health and wellbeing of patients and the general population. Inflammatory activation affects sleep through pro-inflammatory mediators, such as cytokines and prostaglandins, which act on the central nervous system. These molecules can enhance but also disturb sleep, depending mainly on the magnitude of the inflammatory processes. Sleep, in turn, has far-reaching but complex effects on inflammation. Sleep deficiency has been shown to increase inflammatory molecules and activate pro-inflammatory signaling cascades, which may lead to immunopathology when chronically activated. In addition, sleep was shown to affect counter-inflammatory mechanisms, including anti-inflammatory glucocorticoid and pro-resolving resolution pathways. Here, we summarize established concepts and the most recent research in the field of sleep and inflammation. We further highlight the relevance of sleep–immune interactions in the clinical context, with examples related to insomnia, long COVID, and critical care. Finally, practical guidance is given for sleep and immune health in healthcare settings, and a research agenda is provided.