title: Chronobiology of chronic pain: focus on diurnal rhythmicity of neuropathic pain.
abstract: OBJECTIVE
  Although circadian rhythmicity has long been recognized in various nociceptive pain conditions such as arthritis, diurnal pain patterns in neuropathic conditions have only recently been described. The purpose of this article is to review emerging evidence and discuss future research to further understand this phenomenon.
  
  
  RESULTS
  Secondary analyses of neuropathic pain clinical trials demonstrate that pain intensity fluctuations exhibit a distinct diurnal pattern that contrasts that of nociceptive pain conditions. Ongoing preclinical investigations support the phenomenon of circadian pain fluctuations and provide the opportunity to better describe pain chronobiology and to elucidate underlying mechanisms of circadian pain rhythmicity.
  
  
  CONCLUSIONS
  The observation of clinically relevant diurnal pain variability in neuropathic conditions has important implications for future research and treatment of pain. This is an immature research field, and further investigation is needed to better characterize these patterns in more detail, investigate contributory mechanisms, and to develop therapeutic strategies that exploit this phenomenon.
authors.affiliation: aDepartments of Anesthesiology and Perioperative Medicine and Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada bF.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, USA.
authors.forename: Ian
authors.initials: I
authors.lastname: Gilron
authors.forename: Nader
authors.initials: N
authors.lastname: Ghasemlou
mesh_terms: D000700:Analgesics / Q000627:therapeutic use; D059350:Chronic Pain / Q000188:drug therapy / Q000503:physiopathology*; D002909:Chronobiology Phenomena / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D006801:Humans; D009437:Neuralgia / Q000188:drug therapy / Q000503:physiopathology*; D059226:Nociceptive Pain / Q000188:drug therapy / Q000503:physiopathology; D010147:Pain Measurement
chemical_list: D000700:Analgesics