Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Adverse effects
RCT Crossover design 3-armed trial	25 people aged 70 to 89 years with primary insomnia; 20 people completed at least 1 treatment arm	Total number of adverse events 14 days 90 with diphenhydramine 50 mg for 14 nights 90 with placebo	P value not reported Reported as not significant		Not significant