A pragmatic , parallel-group randomized controlled trial of @ adults ( @ F : ( mean @ years ( @-@ years ) ) meeting Diagnostic and Statistical Manual of Mental Disorders , @th Edition ( DSM-@ ) criteria for insomnia disorder , assigned to CBT ( n = @ ; @ F ) , imagery relief therapy ( IRT placebo ; n = @ ; @ F ) , or treatment as usual ( TAU ; n = @ ; @ F ) , was conducted .