Sleeping for two: A randomized controlled trial of cognitive behavioural therapy for insomnia (CBTI) delivered in pregnancy and secondary impacts on symptoms of postpartum depression.

Background: Insomnia in pregnancy is common and highly comorbid with depression.

Objective: To investigate if: 1) depressive symptoms decrease after cognitive behavioural therapy for insomnia (CBTI) delivered in pregnancy, and 2) changes in insomnia symptoms represent a mechanism linking CBT-I treatment and reduced symptoms of postpartum depression.

Methods: A two-arm, single-blind, parallel groups randomized controlled trial (RCT) design was used to evaluate the impact of a 5-week CBT-I intervention adapted for pregnant people with insomnia (N = 62). Participants were eligible if they were pregnant, between 12 and 28 weeks gestation, and met diagnostic criteria for insomnia. Participants completed questionnaires assessing symptoms of insomnia and depression pre-intervention (T1), post-intervention (T2), and six months postpartum (T3). A path analysis model was used to test direct and indirect effects simultaneously.

Results: There was a significant direct effect of CBT-I on postpartum depressive symptoms at T3. Additionally, significant indirect treatment effects on depressive symptoms at T3 emerged, through depressive symptoms at T2 and through improvements in insomnia that persisted from T2 to T3.

Limitations: Limitations to the current study include limited generalizability, the non-depressed sample, and variability in treatment and assessment delivery (in-person vs. online).

Conclusions: CBT-I treatment in pregnancy may indirectly reduce postpartum depressive symptoms, through sustained improvements in insomnia symptoms.