Summary of findings 3.

Melatonin compared with placebo for postoperative anxiety
Patient or population: Patients undergoing elective surgery Settings: Hospital Intervention: Melatonin Comparison: Placebo
Outcomes	Relative effect (95% CI)	No of Participants (studies)	Quality of the evidence (GRADE)
Postoperative anxiety (STAI) Measured 6 hours postoperatively. The range of scores is 20 to 80, the higher scores indicating greater anxiety	‐5.31 (‐8.78, ‐1.84)	73 (2)	⊕⊕⊕⊝ moderate
CI: Confidence interval; STAI: State‐Trait Anxiety Inventory
GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate.

The quality of the evidence is downgraded one level due to the low overall number of participants.