The Effect of Cognitive Behavioral Therapy for Insomnia (CBT-I) on Cardiometabolic Health Biomarkers: A Systematic Review of Randomized Controlled Trials.

Objectives: To assess the effectiveness of Cognitive Behavioral Therapy for Insomnia (CBT-I) on cardiometabolic health biomarkers.

Method: Cochrane CENTRAL, Embase, Medline, and PsycINFO were searched, and records were screened by two independent reviewers. Inclusion criteria were adult population, delivery of CBT-I, randomized controlled trial design, ≥1 cardiometabolic health outcome, and peer-review. Hedge's g effect sizes were calculated, and the quality of the evidence was appraised using the Cochrane Risk of Bias 2 tool.

Results: After screening 1649 records, 15 studies were included (total N = 2067). Inflammatory markers (CRP, IL-6, TNF-α), blood pressure (SBP, DBP), and glycemic regulation (HbA1c) were most frequently reported (in ≥3 studies each). HbA1c and CRP were reduced in the CBT-I group compared to the control group (in 3 studies each). Effects varied or were null for IL-6, TNF-α, SBP, and DBP. Six studies were judged as low, four as moderate, and five as high risk of bias.

Conclusion: CBT-I was most consistently associated with improved HbA1c and CRP, which are relatively temporally stable, suggesting influences on enduring habits rather than short-term behavior changes. High risk of bias limits the interpretation of findings. Methodologically adequate studies are needed to better understand cardiometabolic effects of CBT-I.