ABSTRACT: Background:Sleep deficiency affects a majority of pregnant women with significant impact on daily function, mood, and pregnancy and birth outcomes. This ongoing study combines two evidence-based strategies for improving sleep and mood, mindfulness meditation and cognitive-behavioral therapy for insomnia (CBT-I), in a unique online format to address the particular needs of pregnant women. The purpose of this study is to test the feasibility and estimate the efficacy of this novel 6-week online mindfulness meditation intervention to help pregnant women in remission from depression self-manage insomnia. Methods:This is a two-arm, parallel group randomized controlled trial. A total of 50 pregnant women between 12 and 28?weeks gestation will be recruited from the community and randomly assigned to a mindfulness or education-only control group in a 1:1 ratio. During the study, all participants will complete six weekly online modules, daily sleep diaries, and optional participation in a treatment-specific online discussion forum. Feasibility outcome measures will include study recruitment, retention, intervention adherence (number of online modules completed, number of meditation days per week), and intervention acceptability (8-item questionnaire). The primary clinical outcome measure will be sleep quality measured with the Pittsburgh Sleep Quality Index. Secondary outcome measures will include sleep measured with actigraphy and diaries (sleep efficiency, total sleep time, total wake time), Patient-Reported Outcomes Measurement Information System (PROMIS) measures (fatigue, sleep-related impairment, sleep disturbance); mood (depression, anxiety, positive affect, quality of life); and self-management and behavior change (potential self-efficacy, self-regulation, sleep problem acceptance, and trait mindfulness). Assessments will occur at baseline and post-intervention; an additional acceptability survey will be completed 4?weeks postpartum. Analyses will examine within-group differences in outcome change scores from baseline to post-intervention. Open-ended feedback will be analyzed using qualitative content analysis. Discussion:This research is innovative in addressing sleep in pregnancy using a self-management research design and methods that can be accessible and cost-effective for large numbers of pregnant women. The results from this study will inform intervention refinement and efficacy testing of the intervention in a larger randomized controlled trial. Trial registration:ClinicalTrials.gov, NCT04016428. Registered on 11 July 2019. Updated version registered on 26 July 2019.