internetbased treatment for insomnia a controlled evaluation this study investigated the effects of an internetbased intervention for insomnia participants who met criteria for insomnia n 109 were randomly assigned to either a cognitivebehavioral selfhelp treatment or a waiting list control condition the 5week intervention mainly consisted of sleep restriction stimulus control and cognitive restructuring sleep diary data were collected for 2 weeks at baseline and at posttreatment the dropout rate was 24 n 28 results showed statistically significant improvements in the treatment group on many outcome measures including total sleep time total wake time in bed and sleep efficiency however improvements were also found in the control group overall betweengroups effect sizes were low with the exception of the beliefs and attitudes about sleep scale cohens d 81