Suvorexant is a dual orexin receptor agonist and is currently approved for the 
treatment of insomnia in the United States and Japan. We conducted a systematic 
review and meta-analysis to assess the efficacy and safety of suvorexant for the 
treatment of primary insomnia. We searched PubMed, EMBASE, and the Cochrane 
central register of controlled trials, contacted a relevant pharmaceutical 
company, and accessed websites of the U.S. Food and Drug Administration (FDA) 
and Pharmaceuticals and Medical Devices Agency (PMDA) for published and 
unpublished data. A total of four randomized trials involving 3076 patients with 
primary insomnia were included in our analysis. Our analysis suggested that 
suvorexant was associated with significant improvements in subjective time to 
sleep onset, subjective total sleep time, and subjective quality of sleep at 
1 mo and 3 mo. Somnolence, fatigue, and abnormal dreams were the most common 
adverse effects. We concluded that suvorexant was associated with improvement in 
some sleep parameters and some adverse effects. To determine the place of 
suvorexant in the treatment of insomnia, comparative effectiveness trials are 
needed.