A systematic review of peri‐operative melatonin

Summary We systematically reviewed randomised controlled trials of peri‐operative melatonin. We included 24 studies of 1794 participants that reported eight peri‐operative outcomes: anxiety; analgesia; sleep quality; oxidative stress; emergence behaviour; anaesthetic requirements; steal induction; and safety. Compared with placebo, melatonin reduced the standardised mean difference (95% CI) pre‐operative anxiety score by 0.88 (0.44–1.33) and postoperative pain score by 1.06 (0.23–1.88). The magnitude of effect was unreliable due to substantial statistical heterogeneity, with I2 87% and 94%, respectively. Qualitative reviews suggested the melatonin improved sleep quality and emergence behaviour, and might be capable of reducing oxidative stress and anaesthetic requirements.