Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Jet lag score
Systematic review	142 travellers on eastward flights 4 RCTs in this analysis	Weighted mean subjective jet lag score 30.9 with melatonin 50.7 with placebo	WMD –19.5 95% CI –28.1 to –10.9	Effect size not calculated	melatonin
Systematic review	90 travellers on westward flights 2 RCTs in this analysis	Weighted mean subjective jet lag score 22.3 with melatonin 40.6 with placebo	WMD –17.3 95% CI –27.3 to –7.3	Effect size not calculated	melatonin