2.4. Statistical Analysis
sleep disturbance
This was a two-group pre–post experimental design, in which participants were randomly assigned to the intervention or the control group. For each group, outcome variables were collected at t0 and t1 and subjects who did not fill in the proposed questionnaires at both time points were excluded from the analysis. Questionnaires were scored following the provided guidelines, and, for each questionnaire, internal consistency was assessed via Cronbach’s α coefficient using the Differences between the baseline characteristics of the groups, collected through the background questionnaire, were investigated for each continuous variable by using Linear Mixed Effect (LME) models [For the statistically significant score change, considering an unadjusted A linear model of the number of IM classes attended by each participant on each post–pre difference in questionnaire score (Δ) was also fitted to test the possible dose–response effect using the number of meditation sessions attended (in days) as an explanatory variable, controlling for sex, age, previous meditation experience and consumption of drugs for sleep disturbance treatment. Descriptive statistics are reported as the mean ± standard deviation (SD). All analysis were performed using R 3.5.1 software [