title: Circadian rhythms: from basic mechanisms to the intensive care unit.
abstract: OBJECTIVE
  : Circadian rhythms are intrinsic timekeeping mechanisms that allow for adaptation to cyclic environmental changes. Increasing evidence suggests that circadian rhythms may influence progression of a variety of diseases as well as effectiveness and toxicity of drugs commonly used in the intensive care unit. In this perspective, we provide a brief review of the molecular mechanisms of circadian rhythms and its relevance to critical care. DATA SOURCES, STUDY SELECTION, DATA EXTRACTION, AND DATA SYNTHESIS:: Articles related to circadian rhythms and organ systems in normal and disease conditions were searched through the PubMed library with the goal of providing a concise review.
  
  
  CONCLUSIONS
  : Critically ill patients may be highly vulnerable to disruption of circadian rhythms as a result of the severity of their underlying diseases as well as the intensive care unit environment where noise and frequent therapeutic/diagnostic interventions take place. Further basic and clinical research addressing the importance of circadian rhythms in the context of critical care is warranted to develop a better understanding of the complex pathophysiology of critically ill patients as well as to identify novel therapeutic approaches for these patients.
authors.affiliation: Keenan Research Centre at the Li Ka Shing Knowledge Institute of St Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: Ming-Cheng
authors.initials: MC
authors.lastname: Chan
authors.forename: Peter M
authors.initials: PM
authors.lastname: Spieth
authors.forename: Kieran
authors.initials: K
authors.lastname: Quinn
authors.forename: Matteo
authors.initials: M
authors.lastname: Parotto
authors.forename: Haibo
authors.initials: H
authors.lastname: Zhang
authors.forename: Arthur S
authors.initials: AS
authors.lastname: Slutsky
mesh_terms: D001777:Blood Coagulation / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena; D002940:Circadian Rhythm / Q000502:physiology*; D003422:Critical Care / Q000379:methods; D016638:Critical Illness; D006801:Humans; D007109:Immunity / Q000502:physiology; D007362:Intensive Care Units; D007668:Kidney / Q000378:metabolism / Q000502:physiology; D008099:Liver / Q000378:metabolism / Q000502:physiology; D012143:Respiratory Physiological Phenomena