Mindfulness meditation for insomnia: A meta-analysis of randomized controlled trials
Introduction
Insomnia is a prevalent sleep disorder, characterized by difficulties in initiating and/or maintaining sleep, and is associated with significant distress or daytime impairments, despite adequate sleep opportunity [1]. Sleep plays vital roles in maintaining the well function of brain, immune system, metabolic system and cardiovascular system [2], [3], [4], [5]. Insomnia is closely associated with hypertension, cancer, and psychiatric disorders like anxiety and depression [6], [7], [8], [9]. Insomnia can cause significant distress or impairment in social, occupational, and other functioning. According to recent epidemiological studies, 20ā40% of adults in China, the United States, Spain, Sweden, Japan and other countries suffer from insomnia and 10ā15% of them meet the diagnostic criteria for an insomnia disorder [10], [11], [12], [13]. Therefore, it is very necessary to manage insomnia effectively.
To better understand the role of sleep in daily life, sleep is usually measured by two parameters, sleep quantity and sleep quality. Some measures of sleep are more easily quantifiable, including sleep latency, awakenings at night, sleep duration, etc. However, sleep quality, including depth of sleep, general satisfaction with sleep, etc., is usually investigated by subjective sleep quality indexes [14]. Take Pittsburgh Sleep Quality Index for example, sleep quality is defined as a composite score of seven subcategories: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction [15].
Pharmacotherapy is a traditional treatment for insomnia. The mostly used medicines include benzodiazepines, benzodiazepine-receptor agonists and the first orexin receptor antagonist. Recently, cognitive behavioral therapy is well demonstrated as an efficacious treatment for insomnia [16], [17]. Okajima et al. revealed that cognitive behavioral therapy could reduce insomnia symptoms as well as the daily dose of hypnotic medication in patients with chronic insomnia resistant to pharmacological treatment [18]. In addition to cognitive behavioral therapy, several other promising psychological interventions intended to facilitate sleep health have focused on mindfulness meditation (MM) over the past two decades. Mindfulness refers to a state of conscious that is characterized by an intentional and non-judgmental awareness of present-moment experiences, rather than attempts to alter current experience or to eliminate them from awareness. Higher level of mindfulness is associated with better cognitive performance, physical and mental health, as well as less experience of stress. Mindfulness meditation consists of practice in interactive processes of attention regulation, body awareness, emotion regulation, and changing views regarding self and others [19].
In recent years, there is also some evidence suggesting that consistent practice of MM contributes to the improvement of sleep quality and the reduction of insomnia symptoms [20]. However, there is no systematic review regarding the effects of MM on insomnia. In order to examine the evidence that MM may improve the sleep health of insomnia patients, we carried out this systematic review and meta-analysis on the basis of several randomized controlled trials (RCTs) published up to July 2015.
Section snippets
Literature research
Literature searches were performed in PubMed, EMBASE, the Cochrane Library and PsycINFO from the earliest available dates in the individual databases until July 2015. We developed a PubMed and the Cochrane Library search strategy using medical subject heading (MeSH) terms and text words of key articles that we identified a priority. A similar strategy was carried out in the other electronic sources. The MeSH terms or keywords used in the search included āsleep disordersā or āinsomniaā or āsleep
Study selection
1516 potentially relevant papers were identified, and the process of selection is shown in a PRISMA flow diagram (Fig. 1). Application of inclusion and exclusion criteria resulted in six pioneering RCTs on the efficacy of MM. Some original authors were contacted for additional details of their published studies, but none were available. A total of 330 participants with insomnia were included in the meta-analysis. The diagnoses included chronic, primary insomnia or sleep disturbances [24], [25],
Discussion
This meta-analysis demonstrates that MM may contribute to improving sleep in subjects with insomnia compared to waiting-list control or attention control groups. Specifically, compared to control groups, MM significantly reduced TWT, SOL, PSQI scores and increased sleep quality and sleep efficiency. It should also be noted that the effects of MM on TST did not reach to a significant degree. The reasons may include three aspects: first, some participants in control groups got unexplained
Conflict of interest statement
We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work. There is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled.
The following is the supplementary data related to this article.
Acknowledgements
This research was supported by National Natural Science Foundation of China (31371200, 81571169) and Twelfth Medical Research Foundation (BWS14J021).
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