What the proper treatment does
Two pooled analyses, and no number is quoted from either, because none was read off the papers for this course. What follows is the direction of the findings.
What the research says
Trauer JM, Qian MY, Doyle JS, Rajaratnam SMW, Cunnington D (2015). Cognitive behavioral therapy for chronic insomnia: a systematic review and meta-analysis. Annals of Internal Medicine, 163(3), 191 to 204 doi
Pools trials of the multi part behavioural treatment for long standing insomnia in adults. People fell asleep faster, spent less time awake during the night, and spent more of their time in bed actually asleep. No figure is quoted here because none was read off the paper.
van Straten A, van der Zweerde T, Kleiboer A, Cuijpers P, Morin CM, Lancee J (2018). Cognitive and behavioral therapies in the treatment of insomnia: a meta-analysis. Sleep Medicine Reviews, 38, 3 to 16 doi
The larger and more recent pooled analysis of the same family of treatments, reaching the same direction. The point worth taking from it is that the benefit comes from the combination of components working together, which is why a single tip on its own tends to do so little.