The role of behaviour-change theory in sleep interventions with emerging adults (aged 18-29 years): a systematic review and meta-analysis.

Previous systematic reviews and meta-analysis of sleep interventions with young adults have not reached consensus on what contributes to their efficacy. Behaviour-change theories may influence the efficacy of interventions; hence, the aim of this research was to investigate the role of such theories in sleep interventions with this population. Six electronic databases and reference lists were searched (April-May 2021) for published sleep behaviour-change interventions with emerging adults (aged 18-29 years) that used control groups. A selection of 20 studies fulfilled the inclusion criteria, but only six were based on behaviour-change theories. Meta-analysis was run with eight studies, as the others had a high risk of bias or did not present the necessary data to calculate Hedges' g. The estimation of a random effects model for the studies showed a small effect in the sleep quality of the participants in the experimental group (g = -0.26; 95% confidence interval -0.42 to -0.09), with low levels of heterogeneity (I  = 21%), and a small 95% prediction interval (-0.59 to 0.08). Although we could not examine theory or any other moderators of the effect, a qualitative analysis of the behaviour-change techniques present in the interventions leads us to hypothesise that there is not a direct link between behaviour-change techniques and the success of the intervention. Other characteristics of the interventions may be linked to their variable levels of efficacy and should be investigated in the future, as for now there are no answers as to what the key is for successful sleep interventions.