The small number of studies examining the safety and effectiveness of only limited styles and types of yoga for improving insomnia and sleep quality impairment among patients, coupled with the lack of regulation and wide variability of yoga offerings, substantially increases the chance that patients may spend a sizable amount of time, energy, and money participating in yoga programs that may not be safe, effective, or meet their specific needs. For example, yoga in a room heated to over 100 degrees may be contraindicated for some patients, and vigorous yoga may result in excessive muscle soreness and joint pain, increasing insomnia, or sleep quality impairment. These considerations need to be considered by oncology practitioners who may be recommending yoga to their patients so that they can ensure appropriate classes are taken.
Despite their limitations, these phase I–III studies collectively support the benefits of yoga, demonstrating that:
- cancer patients can safely participate in yoga during and after cancer treatments;
- yoga interventions are feasible in a variety of cancer centers and community-based yoga studios;
- participating patients find yoga programs enjoyable and beneficial;
- participation in low- to moderate-intensity yoga that incorporates Gentle Hatha and Restorative postures, breathing and meditation exercises ranging from one to five sessions/week for 50–120 minutes per session over a period of 4 to 26 weeks may lead to improvements in insomnia and sleep quality impairment; and
- participation in standardized yoga programs designed explicitly for cancer patients experiencing insomnia will reduce the symptoms of insomnia they experience.
Referral resources can help patients connect with the most-qualified and competent yoga instructors in their community, including those who have special training and experience in working with cancer patients, or individuals with other chronic medical conditions. Patients may also benefit from understanding that the styles and types of yoga that have been scientifically tested in a randomized clinical trial and shown to be safe and effective for improving sleep among cancer patients include a low- to-moderately intense program, consisting primarily of Gentle Hatha and Restorative postures, combined with breathing and meditation exercises.
When screening patients for insomnia symptoms and making clinical recommendations about the use of yoga for managing insomnia, research suggests yoga is effective for individuals who reported mild-to-moderate sleep quality impairment, as well as clinical insomnia, who continue to report insomnia symptoms after trying pharmaceutical treatments, who demonstrate more than 1 hour of wakefulness in the middle-of-the night, who have poor sleep efficiency (60 % or lower), or who have some combination of these characteristics. Patients with these characteristics were shown to derive the greatest benefits from participation in yoga— specifically in improved sleep and reduced medication use.
While a large, multicenter phase III trial and five additional smaller RCTs have shown that yoga improves sleep in cancer patients, the variability across studies and the inherent limitations in the literature limit the extent to which yoga can be considered effective for treating insomnia or sleep quality impairment among cancer patients. Further research is needed to determine whether yoga is equal to, or superior to, existing gold standard treatment for insomnia and sleep quality impairment, such as CBT-I. Future clinical trials need to employ reliable and validated patient-reported outcomes of insomnia and sleep quality impairment, along with objective measures of insomnia and sleep quality impairment, such as actigraphy and polysomnography. There is also a lack of studies that include long-term, follow-up assessments (e.g. 3, 6, 9, and 12 months post intervention) to determine the duration and magnitude of any sleep benefits derived from yoga. In addition, researchers should make an effort to standardize their yoga program so that it can be replicated and reproduced for patients.
Another goal of future research should be to determine which components of yoga (e.g. postures, breathing, or meditation) are most effective in treating sleep disorders by using only separate components. In addition, mechanistic studies are needed to elucidate the biopsychosocial pathways through which yoga exerts a positive influence on sleep and other toxicities related to cancer and its treatments, such as fatigue, functional decline, cognitive impairment, and deregulated immune function, among others. Furthermore, in the US and other Western nations, yoga is most popular among white females, typically of higher socioeconomic status. Future research is needed to investigate ways to increase yoga participation among racially, economically, socially, and culturally diverse patients, as well as older and male cancer patients. Trials are also needed to compare the efficacy of yoga to other modes of exercise, such as walking and resistance training, for improving sleep. Research shows that the effects of behavioral interventions, such as yoga, may be enhanced by enlisting a care partner to participate with them. Moreover, care partners often tend to higher levels of psychologic distress, such as anxiety and depression. Trials are needed that extend yoga to these care partners (e.g. sister, brother, mother, father, child, spouse, or friend) who provide unpaid care and support to the patient at significant expense to their own health throughout the cancer experience. The benefits this type of study may be twofold, both enhancing the intervention for the patient and reducing distress for the care partner.