V ambulantni študiji primerjave s placebom, randomizirani, dvojno slepi, s placebom kontrolirani, z dvotedenskim uvajalnim obdobjem, s 3- tedenskim trajanjem in dvotedenskim obdobjem odtegnitve, je bil odstotek bolnikov, ki so pokazali klinično pomembno izboljšanje tako v kakovosti spanja kot jutranji budnosti 47 % v skupini, ki je jemala Circadin, v primerjavi s 27 % v skupini, ki je jemala placebo.
In an outpatient study with 2 week run-in baseline period with placebo, a randomised, double blind, placebo controlled, parallel group treatment period of 3 weeks and 2 week withdrawal period with placebo, the rate of patients who showed a clinically significant improvement in both quality of sleep and morning alertness was 47 % in the Circadin group as compared to 27 % in the placebo group.