A comparative study between oral melatonin and oral midazolam on preoperative anxiety, cognitive, and psychomotor functions

BACKGROUND & AIMS: Melatonin, a naturally occurring hormone in the human body, has been reported to cause preoperative anxiolysis and sedation without impairing orientation. The aim of the following study was to evaluate and to compare the effects of oral melatonin and oral midazolam on preoperative anxiety, sedation, psychomotor, and cognitive function. MATERIALS AND METHODS: A study conducted on 120 patients aged 16-55 years, of American Society of Anesthesiologists Grade 1 and 2 posted for elective surgery, with each group of melatonin, midazolam, and placebo comprising 40 patients. Patients were given either 0.4 mg/kg oral melatonin or 0.2 mg/kg oral midazolam or a placebo 60-90 min before induction. Preoperative anxiety was studied before and 60-90 min after giving medications using visual analog scale (VAS) anxiety score, orientation score, and sedation score. Psychomotor and cognitive functions were studied using the digit symbol substitution test (DSST) and trail making test (TMT) tests. Data were analyzed using Chi-square test or Kruskal–Wallis analysis of variance and the value of P < 0.05 was considered as statistically significant. RESULTS: Changes in VAS anxiety scores were significant when melatonin was compared with placebo (P = 0.0124) and when midazolam was compared with placebo (P = 0.0003). When melatonin was compared with midazolam, no significant difference (P = 0.49) in VAS anxiety scores was observed. Intergroup comparison of sedation scores showed melatonin (P = 0.0258) and midazolam (P = 0.0000) to be statistically significant when compared with placebo. No changes in orientation scores occurred in melatonin and placebo group. Change in DSST scores and TMT scores were seen to be significant only in midazolam group. CONCLUSION: Oral melatonin 0.4 mg/kg provides adequate anxiolysis comparable to that of oral midazolam. Unlike midazolam, oral melatonin 0.4 mg/kg does not impair the general cognitive and psychomotor function especially cognitive aspects such as working memory, memory retrieval, sustained attention, and flexibility of thinking.