Statistical methods for primary and secondary outcomes {20a}
REGRESSION, SECONDARY
The primary outcome of the proposed study is the change in the mean sleep duration from baseline to 8 weeks. The study sample size has been determined based on the primary analysis of covariance (ANCOVA) that will compare mean sleep duration at 8 weeks, with statistical adjustment for the baseline sleep duration and the sex and age randomization strata. The proposed ANCOVA approach is recommended for the evaluation of treatment effects on continuous outcomes in randomized trials because it optimally accounts for random imbalances in the outcome at baseline and regression to the mean, thus providing superior statistical power compared to the analyses of change scores or follow-up scores without adjustment for baseline levels [The main secondary outcome for this study is the change in SBP from baseline to 8 weeks. Evaluation of the 24-h SBP outcome at 8 weeks will assure that few patients will have modified their antihypertensive medication regimen over the 8-week interval prior to the primary outcome assessment.Evaluation of the 24-h SBP outcome at 8 weeks will assure that few patients will have modified their antihypertensive medication regimen over the 8-week interval prior to the primary outcome assessment. Similar ANCOVA models as used with sleep duration will also be used to evaluate the acute effects on this and other numeric secondary and tertiary outcomes.We will use linear mixed models [