Summary of findings 2.

Melatonin compared with midazolam (BZD) for preoperative anxiety
Patient or population: Patients undergoing elective surgery Settings: Hospital Intervention: Melatonin Comparison: Midazolam
Outcomes	Relative effect (95% CI)	No of Participants (studies)	Quality of the evidence (GRADE)
VAS (0 to 100 mm) measured approximately 90 min after premedication 0: no anxiety 100: maximum anxiety possible	‐1.18 (‐2.59, 0.23)	122 (2)	⊕⊕⊝⊝ low
CI: Confidence interval; VAS: Visual Analogue Scale
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 two levels due to the risk of bias in the included studies, the wide confidence interval of one study and the relatively low overall number of participants.