Statistical analysis
REGRESSION
The sample size estimate allowed for 20% attrition and noncompliance to provide ≥ 80% power and maximum type I error of 5% to detect a minimal difference of 1.6 point improvement in subjective sleep quality as measured by the ISI sleep scale between cohorts. Generalized linear models were used to compare scores of the outcome measures between cohorts. Paired student t-tests were used to assess difference from baseline to endpoints for each group. Regression models were used to control for covariates (i.e., age, gender, race, compliance, and medication use). All analyses at endpoints were based on intention-to-treat principle. SAS software for Windows version 9.4 (SAS Institute, Cary, NC) was used to carry out all statistical analyses. 