Clinical review
A systematic review of insomnia and complementary medicine

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Summary

In concert with growing public interest in complementary and alternative medicine (CAM), these therapies and products have been increasingly studied over the past two decades for the treatment of sleep disorders. While systematic reviews have been conducted on acupuncture and valerian in the treatment of insomnia, to date no comprehensive review has been conducted on all major CAM treatments. We sought to address this via a rigorous systematic review of hypnotic CAM interventions, including herbal and nutritional medicine, acupuncture, acupressure, yoga, tai chi, massage, aromatherapy and homoeopathy. The electronic databases MEDLINE (PubMed), CINAHL, PsycINFO, and The Cochrane Library were accessed during late 2009 for CAM randomized controlled trials (RCTs) in the treatment of chronic insomnia. Sixty-four RCTs were identified, of which 20 studies involving eight CAM interventions met final inclusion criteria. Effect size calculations (where possible) and a quality control analysis using a modified Jadad scale were undertaken. Many RCTs lacked methodological rigor, and were commonly excluded due to small sample size or an inadequate control condition. Among the studies that met inclusion criteria, there was evidentiary support in the treatment of chronic insomnia for acupressure (d = 1.42–2.12), tai chi (d = 0.22–2.15), yoga (d = 0.66–1.20), mixed evidence for acupuncture and L-tryptophan, and weak and unsupportive evidence for herbal medicines such as valerian. Surprisingly, studies involving several mainstream CAM therapies (e.g., homoeopathy, massage, or aromatherapy) were not located or did not meet basic inclusion criteria. If CAM interventions are to be considered as viable stand-alone or adjuvant treatments for sleep disorders, future researchers are urged to use acceptable methodology, including appropriate sample sizes and adequate controls. RCTs evaluating other untested CAM therapies such as massage, homoeopathy, or osteopathy are encouraged, as is the exploration of using CAM therapies adjuvantly with conventional therapies.

Introduction

Periods of sleep disturbance due to acute stress or environmental change are common human experiences, while chronic idiopathic insomnia is an abnormal condition that presents a major health burden. The prevalence of general sleep disturbance experienced by people over a year is estimated at approximately 85%, while the estimate of diagnosed chronic insomnia is estimated at around 10%.1 Other estimates have found this to be higher, with the United States National Health Interview Survey in 2002 revealing a 12-month prevalence of 17.4% of adults with self-reported insomnia or having trouble sleeping.2 As in the case of mood and anxiety disorders, females have a slightly higher prevalence than males of primary insomnia.*2, 3 The economic cost of sleep disorders is immense, with an estimate of the direct cost of insomnia in the United States approximating US$13.93 billion in 1999.4 Interestingly, most of this cost was service-based (especially for nursing home costs), and only a fraction was from prescription costs.

Conventional approaches to the treatment of chronic insomnia usually involve either pharmacotherapies or psychological interventions. Pharmaceutical hypnotics are the primary first-line pharmacotherapy used to treat chronic insomnia.5 The use of benzodiazepines such as diazepam and related drugs, or non-benzodiazepine hypnotics e.g., zolpidem or zopiclone are preferred currently over older barbiturates which can cause death in cases of overdose.5 With respect to benzodiazepines, although a relatively safe class of medication, concerns exist over dependency, and currently most guidelines endorse only short-term use for insomnia. Sedating antipsychotics, such as olanzapine or quetiapine, and sedating antidepressants, including the older tricyclic drugs, are also commonly prescribed ‘off label’ for chronic insomnia, particularly in later life.6 The use of these drugs has the potential to cause serious adverse effects.7 Whilst many authorities recommend the use of conventional non-pharmacological interventions including behavior modification and sleep hygiene techniques,8 many people with insomnia find these difficult to successfully implement. While pharmacotherapies and psychological interventions are currently the mainstays of conventional treatment, interest in the use of alternative therapies and products for insomnia has grown over the past two decades due to range of motivational factors. CAM users advocate the use of these therapies due in part to beliefs that CAM provides them with an active role in their health, CAM therapies treat the “whole person”, and that conventional medicine was ineffective for their health problem.9 An holistic approach however may not necessarily be the sole domain of CAM, as orthodox medical clinicians may use an integrative approach combining psychological, lifestyle and pharmacological interventions.

CAM use is prevalent by sufferers of psychiatric disorders, commonly for the management of depression, anxiety, or insomnia.10, 11, 12 An analysis of the United States National Health Interview Survey data from 2002 by Pearson et al. (2006) revealed that of the 17.4% of adults (N = 93 386) reporting insomnia or regular sleep disturbance in the preceding month, 4.5% (of that population) used CAM to improve their sleep.2 This result extrapolated to 1.6 million non-institutionalized civilian United States citizens. Biologically-based products such as herbal or nutritional medicine, and mind–body therapies such as tai chi or yoga, were the most commonly used interventions. Fifty-six percent reported that CAM was very important to maintaining their health and well-being, while 72% stated that they believed that CAM helped their insomnia “a great deal” or “some” (49% and 33%, respectively). Approximately sixty percent reported use of CAM to their conventional medical practitioner. Younger, more educated persons were more likely to use CAM to treat their insomnia.2

The main CAM research on insomnia to date has involved acupuncture and acupressure, and the herbal medicine valerian. Notable systematic reviews and/or meta-analyzes on acupuncture and/or acupressure are by Huang et al.,13 Yeung,14 Cheuk et al.,15 and Chen et al.16 These reviews tend to support the use of acupuncture or acupressure, however they all point to concerns over inconsistent results and heterogeneous methodology. To highlight this, the Chen et al. review revealed that five out of six studies had a Jadad quality rating of only one out of five. Noteworthy reviews of valerian have been conducted by Taibi et al.17 and Bent et al.18 Both reviews outline mixed evidence for the herbal medicine, and conclude that no firm evidence currently supports valerian in the treatment of insomnia due to poor methodology and many studies revealing negative results on various outcome measures. Reviews on older populations (which tend to have a higher prevalence of sleep disturbance) by Meeks et al.19 and Gooneratne20 support the use of various CAM interventions, however both encourage further research to confirm this due to many studies having methodological shortcomings.

While these reviews illuminate the evidence in their respective areas, to date no systematic review exists providing a rigorous review of randomized controlled trials (RCTs) of all major CAM interventions on the treatment of chronic insomnia in adults. Accordingly, we conducted the first comprehensive systematic review of this area. In this review we detail the structure of the systemic review process, and provide an analysis of the individual studies meeting inclusion criteria (methodology, results, and quality), in addition to calculating effect sizes where possible. We then critically discuss our findings and summarize the evidence for the use of CAM in treating insomnia. We then outline potential steps forward in improving research and clinical outcomes in this area.

Section snippets

Methods

The electronic databases MEDLINE (PubMed), CINAHL, PsycINFO, and The Cochrane Library were accessed during late 2009 (see Fig. 1 for systematic review flowchart). PubMed was searched using the terms “insomnia” OR “sleep disorders” OR “sleep disturbances” OR “sleep initiation” OR “sleep maintenance” AND 16 major CAM therapies e.g., “acupuncture” OR “yoga” AND 20 major CAM interventions e.g., “valerian” OR “L-tryptophan”. Papers that met the inclusion criteria were RCTs of sufficient

Overview of results

Out of 506 located potential studies in the field of CAM and insomnia, 64 were found to be RCTs. As detailed in appendix 1, 44 studies were eliminated due to small sample size (n = 14); non-English (n = 14); no adequate control (n = 13); comorbidity (n = 6); insufficient duration (n = 3); healthy sample (n = 2); use of isolated constituents (n = 1); diagnosis jet lag (n = 1); insufficient reporting (n = 1); no insomnia scale (n = 1). This left 20 clinical trials (involving eight CAM interventions listed in Table 1

Discussion

To our knowledge this is the first comprehensive systematic review of CAM randomized controlled clinical trials in the treatment of chronic adult insomnia. Although the review found substantial clinical trial literature, the presence of basic methodological weaknesses led to the exclusion of many studies. Only 20 out of 50 English language RCTs met our inclusion criteria. In many herbal medicine RCTs (mainly involving valerian), a small sample size and/or short study duration was employed by

Acknowledgements

Dr Jerome Sarris is funded by an Australian National Health & Medical Research Council fellowship (NHMRC funding ID 628875), in a strategic partnership with The University of Melbourne and the National Institute of Complementary Medicine at Swinburne University of Technology.

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