An Overview of the Methods Used to Measure the Impact of Mindfulness-Based Interventions in Sleep-Related Outcomes.

 Systematic reviews and metanalyses have shown that mindfulness-based interventions can have positive effects on health, such as reducing anxiety, depression, and chronic pain. However, their effect on sleep-related outcomes is not yet well established. Sleep can be assessed subjectively (questionnaires, sleep logs, self-reporting) and/or objectively (actigraphy, polysomnography, biological markers), and outcomes may differ depending on which type of assessment is used.  In this study, we present a literature overview on mindfulness and sleep, innovatively presenting and discussing studies that address sleep subjectively and objectively.  The search was undertaken using four databases (Pubmed Medline, Scopus, Web of Science, Psychinfo) in September 2019, and repeated in May 2021. Studies were analyzed through a two-step process: (1) reading titles and abstracts, and (2) full text analysis that met the review's eligibility criteria, with the final sample comprising 193 articles. We observed a growth in the number of studies published, particularly since 2005. However, this was mostly due to an increase in studies based on subjective research. There is a moderate to nonexistent agreement between objective and subjective sleep measures, with results of subjective measures having higher variability and uncertainty.We identified 151 articles (78%) using an exclusively subjective sleep evaluation, which can cause a misperception about mindfulness effects on sleep.  Future studies should place greater emphasis on objective measurements to accurately investigate the effects of mindfulness practices on sleep, although subjective measures also have a role to play in respect of some aspects of this relationship.