I kliniske forsøg (hvor i alt 1361 patienter tog Circadin, og 1247 patienter tog placebo) rapporterede 37, 0% af de patienter, der fik Circadin, en bivirkning, sammenlignet med 31, 8% af de patienter der fik placebo.
In clinical trials (in which a total of 1361 patients were taking Circadin and 1247 patients were taking placebo), 37.0% of patients receiving Circadin reported an adverse reaction compared with 31.8% taking placebo.