In a systematic review and meta-analysis published in "Sleep Medicine Reviews", cognitive-behavioral therapy for insomnia (CBT-I) exhibited superior effectiveness for treatment of insomnia with normal sleep duration (INS) phenotype in comparison with insomnia disorder with objective short sleep duration (ISS) phenotype, with a 20% greater remission and 30% greater response. The first-line therapeutic option for insomnia has been suggested as CBT-I.

A separate subtype from the INS phenotype called ISS may respond differently to treatment. Using the PICOS principle, PubMed, EMBASE, the Cochrane Library, and ClinicalTrials.gov were explored for studies comparing the effectiveness of CBT for people with the ISS phenotype and those with the INS phenotype. Nine studies with 612 insomnia-affected people were recognized. There were 270 ISS phenotype volunteers and 342 INS phenotype volunteers.

The key finding was that CBT-I was more effective for treating the INS phenotype than the ISS phenotype, with a 30% higher response and 20% higher remission. The secondary outcomes illustrated similar outcomes. The ISS phenotype's treatment response varied greatly from the INS phenotype's. Future studies are required to determine the best way to combat insomnia disorder with the ISS phenotype and to determine whether reducing physiologic arousal will be necessary to get better outcomes.