THEORETICAL REVIEW Postoperative sleep disruptions: A potential catalyst of acute pain? Florian Chouchou a, b, c, * , Samar Khoury a, b, c , Jean-Marc Chauny d, e , Ronald Denis d, e , Gilles J. Lavigne a, b, c, d, e a Faculty of Dental Medicine, Université de Montréal, Montreal, Quebec, Canada b Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada c Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada d Trauma Unit, Surgery Department, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec, Canada e Emergency Unit, Surgery Department, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec, Canada article info Article history: Received 27 February 2013 Received in revised form 8 July 2013 Accepted 9 July 2013 Available online 24 September 2013 Keywords: Sleep Pain Surgery Postoperative Opioids summary Despite the substantial advances in the understanding of pain mechanisms and management, postoperative pain relief remains an important health care issue. Surgical patients also frequently report postoperative sleep complaints. Major sleep alterations in the postoperative period include sleep fragmentation, reduced total sleep time, and loss of time spent in slow wave and rapid eye movement sleep. Clinical and experi- mental studies show that sleep disturbances may exacerbate pain, whereas pain and opioid treatments disturb sleep. Surgical stress appears to be a major contributor to both sleep disruptions and altered pain perception. However, pain and the use of opioid analgesics could worsen sleep alterations, whereas sleep disruptions may contribute to intensify pain. Nevertheless, little is known about the relationship between postoperative sleep and pain. Although the sleepepain interaction has been addressed from both ends, this review focuses on the impact of sleep disruptions on pain perception. A better understanding of the effect of postoperative sleep disruptions on pain perception would help in selecting patients at risk for more severe pain and may facilitate the development of more effective and safer pain management programs. Ó 2013 Elsevier Ltd. All rights reserved. Introduction Despite significant advances in the understanding of pain mechanisms and innovative developments of analgesic and anes- thetic agents, acute postoperative pain control remains a challenge in about one-third of surgical patients [1]. In a large Dutch cohort of 1490 surgical patients who received postoperative pain treatment, patients still experienced moderate to severe pain on the day of the surgery, which continued in 15% at four days after surgery [2,3]. Acute postoperative pain was also followed by chronic pain, which was severe in about 2e10% of postoperative patients [4]. In an attempt to improve postsurgical pain management, studies have identified several potential predictors of postoperative pain as well as several preoperative and psychological factors such as pain experience, age, duration, surgery, and previous chronic sleep problems (Fig. 1) [3,5e8]. Mamie et al. [7] found that, of several factors known to affect postoperative pain, chronic sleep complaints before surgery constituted the strongest determinant of pain at rest postoperatively. Moreover, patients frequently report postoperative sleep disturbances in response to surgical stress, and some electroencephalographic studies have demon- strated decreased total sleep time in both slow wave sleep (SWS) and rapid eye movement (REM) sleep duration as well as increased sleep arousals [9]. Furthermore, clinical observations largely indi- cate that sleep and pain interact bidirectionally. Thus, clinical and experimental studies have demonstrated that sleep disturbances exacerbated pain perception in healthy subjects [9e24] and in several pain conditions [25,26], whereas pain [27e30] and pain management with opioids [31,32] may disturb sleep. Surgical stress appears to be a major contributor to both sleep disruptions and altered pain perception, whereas sleep disturbances may alter pain perception and intensify pain postoperatively, and pain and the use of opioid analgesics may increase alterations in the quality and quantity of sleep. Although this bidirectional relationship between postsurgical sleep and pain has been addressed in this review, we focus on updating the state of the knowledge on the potential role of sleep disturbances in postsurgical pain exacerbation in the aim of helping in selecting patients at risk for more severe pain and facilitating the development of more effective and safer pain management programs. * Corresponding author. Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, 5400 Gouin Blvd. West, Montreal, Quebec H4J 1C5, Canada. Tel.: þ1 514 338 2222x7707; fax: þ1 514 338 3892. E-mail addresses: florianchouchou@gmail.com, florianchouchou@hotmail.fr (F. Chouchou). Contents lists available at ScienceDirect Sleep Medicine Reviews journal homepage: www.elsevier.com/locate/smrv 1087-0792/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.smrv.2013.07.002 Sleep Medicine Reviews 18 (2014) 273e282