A study to investigate if melatonin can improve sleep in hospital after abdominal surgery.

INTERVENTION: Melatonin 5mg wafer once daily sublingual whilst in hospital from day 1 post surgery up to 7 days or until discharge if prior to 7 days. The doses will be prescribed via the electronic medication chart and this will be reviewed to confirm compliance to administration. CONDITION: Abdominal surgery;Sleep disturbance; ; Abdominal surgery ; Sleep disturbance Alternative and Complementary Medicine ‐ Other alternative and complementary medicine Surgery ‐ Other surgery PRIMARY OUTCOME: The primary efficacy outcome is a difference in Patient‐Reported Outcome Measurement Information System (PROMIS) Sleep Disturbance 8a score between the 2 arms of the study.[At day 3 post surgery.] SECONDARY OUTCOME: All‐cause mortality[By day 30 as recorded in medical record or reported by treating surgeon.] Difference between groups for mean length of hospital stay (days)[As recorded in medical record for index admission, up to the time of suitability for surgical discharge to home or rehabilitation.] Incidence of delirium as defined by a clinical diagnosis of same by treating team.[Assessed from the medical record up to the time of hospital discharge or discharge from surgical service.] Incidence of post‐operative surgical complications graded by the Clavien‐Dindo Classification of Surgical Complications.[Up to day 30 post‐op as recorded in medical record.] Mean difference between groups for serum cortisol levels[Levels measured at baseline, day of surgery and day 1, 2, 3 post‐operatively as recorded from the medial record.] Patient reported quality of life scores[Measured pre‐operatively and at day 30 post‐op using the EQ‐5D‐5L.] INCLUSION CRITERIA: All English‐speaking patients 18 years and over undergoing elective/semi‐elective major abdominal surgery with an anticipated length of stay greater than 48 hours.