According to the American Academy of Sleep Medicine, psychological and behavioral treatment for insomnia could include stimulus control therapy, relaxation training, cognitive behavior therapy, sleep restriction therapy, biofeedback and paradoxical intention ( https://j2vjt3dnbra3ps7ll1clb4q2-wpengine.netdna-ssl.com/wp-content/uploads/2017/07/PP_BTInsomnia_Update.pdf ).
I would try to find a therapy manual for CBT-I and go from there.
As for the validation, I would use subjective sleep measures (sleep diaries), objective measures (actigraphy, maybe even polysomnography, if available) and psychometric testing (either the ISI or the PSQI for insomnia symptoms, the BDI-II and the MADRS or the HAMD for symptoms of depression, and maybe a measure for daytime sleepiness like the ESS).