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Does Yoga Practice Reduce Stress?
September 23, 2007
Today’s society places great emphasis on vast achievement, progression, and motivation. It seems that no task is too gigantic for us to handle. Americans, thriving on caffeine and adrenaline, go about their crammed schedules, taking on the world all while putting dinner on the table at the end of the day. Undoubtedly, these values have benefited American society; however, this hectic lifestyle does not come without the all too familiar byproduct: stress. In a world where stress is practically unavoidable, we are constantly seeking new ways to reduce stress. The practice of yoga has recently become popular among many Americans and is constantly advertised in conjunction with the reduction of stress. Though many of these claims seem plausible, we must look further into the scientific research on yoga practice and stress reduction in order to answer this important question.
What is Stress Anyway?
Image 1: (www.ruralstress.ca/inside/ruralstress.html)
The same response that enables us to focus for that last minute assignment or push through the final mile in a marathon, if chronically prolonged, can also cause negative effects. The stress response, also known as the “fight or flight” reaction, is both biochemical and psychological. The onset of this response comes from a physical or mental threat. This activates the body’s sympathetic nervous system which is responsible for reacting to emergencies (www.will-harris.com/yoga/yoga_and_stress.html). Many of the systems in the body are affected as a result of this sympathetic activation. The hypothalamus, a gland in the brain, alarms the body and immediately hormones such as adrenaline and cortisol are released. Some of the immediate effects of the stress response include:
· Increased heart rate
· Increased blood pressure
· Increased and enhanced use of glucose
· Altered immune system response
· Suppression of the digestive system
· Suppression of the reproductive system
“All this arousal in an emergency becomes pathological if it is not turned off when the threat is over” (www.will-harris.com/yoga/yoga_and_stress.html). These emergencies can result from physical or psychological threats and the degree to which we have control over them varies. If the stress response is persistent over long periods of time it can disrupt many normal bodily processes and functions, increasing risks to various physical and mental illnesses, as well as, resulting in other negative complications (www.mayoclinic.com/print/stress/SR00001/METHOD=print).
Where Does Downward Dog Come Into Play?: The Claims-
Image 2 from: (www.yoga.net.au/asana)
Reduction in stress levels is one highly advertised benefit of regular yoga practice. Advocates of this claim maintain that yoga can provide a way for the body to release stress through expelling tension and frustration. Though there are many types of yoga practice, essentially there are two important elements to any yoga practice: the physical, through various postures and breathing control, and the spiritual or mental aspect, focusing on concentration techniques. The postures are formulated to balance the body, not only literally, but also internally through the different systems of the body (www.helpguide.org/mental/stress_relief_meditation_yoga_relaxation.htm). Advocates also believe that stress reduction is made possible by enabling your body and mind to shift focus from the stressors in your life to the poses that require balance and concentration (www.mayoclinic.com/health/yoga/CM00004). The YogaAlliance even states that yoga has been shown to lower cortisol levels, the levels that are increased through “fight or flight.” To counteract the sympathetic nervous system, the body activates the parasympathetic nervous system or the relaxation response. It is this system that is responsible for bringing all the heightened bodily systems back down to normal. The emphasis on slow and deep breathing in yoga practice can help to activate the parasympathetic system, thus helping the body return to homeostasis (www.yogavillagepa.com/faq/YogaStressRelief.pdf).
The Scientific Evidence-
The study of the effects of yoga practice on stress reduction is relatively new to the scientific realm. Consequently, there are few scientific studies that are able to effectively and systematically link yoga with stress reduction. One study that does seem to look at this phenomenon was a study published in 2006 conducted by Eckert et al. Their objective was to compare yoga and relaxation as a treatment to reduce subject stress, anxiety, blood pressure and improve quality of life. One-hundred and thirty-one subjects were randomly assigned to either ten weekly, one hour sessions of relaxation or hatha yoga. To measure the outcomes, the experimenters utilized the State Trait Personality Inventory sub-scale anxiety, General Health Questionnaire, and the Short Form-36. The results indicated that in both groups stress, anxiety, and quality of life scores improved. Yoga was seen as more effective in improving mental health, but there were no differences between the conditions in levels of stress and anxiety, although both improved (Eckert et al., 2006). This study can offer insight into whether yoga affects stress; however, it does not come without its questions either. One drawback of this study is that subjects tested had only mild to moderate levels of stress, inferring that extremely stressed subjects were excluded from the study. Stress also largely differs from subject to subject and each person deals differently with the stressors in their life. The stress might have subsided not because of the intervention but just simply because over time subjects’ stress levels decreased. Another critique of the study is the fact that questionnaires were used in determining stress levels pre and post intervention. Along with this comes the problem of honesty. There is a possibility that subjects lied, either intentionally or unintentionally, about their stress levels before and after the intervention.
There have also been more specific studies done on yoga practice, such as a study conducted by Oken et al. in 2006 which focused on the effects of yoga in healthy seniors on cognition and quality of life. Stress reduction is encompassed under the quality of life category. In this study, one-hundred and thirty-five healthy men and women aged 65-85 years were randomly assigned to three conditions: yoga, exercise, and wait-list control. The study was conducted over six months and yoga was practiced in one class a week along with home practice. Self-report measures were employed to assess stress levels. Results indicated that there was no improvement in cognitive functioning; however, there were significant improvements in quality of life measures (Oken et al., 2006). The Oken study is credible; however, it has a low external validity, that is, the results are difficult to generalize to a larger population. Some drawbacks include the fact that the yoga was designed for seniors, indicating a modified yoga program. Also, the study even alluded to the problem of other confounds, such as socialization, placebo, and self-efficacy, as being possibly responsible for the significant effect in quality of life (Oken et al., 2006).
Their have been few studies that have focused on just the practice of yoga alone as a variable. More scientific studies have been tested with an intervention called Mindfulness-Based Stress Reduction (MBSR). This is a program that incorporates relaxation, meditation, yoga practice, and daily home practice of the techniques. Even though these studies do not focus on yoga solely, because they encompass the same essential ideas they can provide insight into some possible benefits. Two studies, by Carlson et al. have focused on MBSR and its effect on mood and symptoms of stress in cancer patients. These are worth mentioning because obviously any serious illness, such as cancer, is a massive onset of stress. In both studies subjects were enrolled in MBSR, one for seven weeks and one for eight. Both studies indicated that post-intervention resulted in a decrease in stress symptoms. As with most, there are some major limitations in these studies. The population was fairly small, with one study having 42 subjects and the other having ninety. Also, it is not possible to draw conclusions merely about yoga practice because it was not the sole intervention. In both studies, other behaviors changed as the studies progressed, most notably the quality of sleep for patients. The stress reduction results could be indicative of these variables, as well (Carlson et al., 2000 and Carlson et al., 2002).
Another scientific study conducted between 1997 and 1999 by Brainard et al., also looked at the effects of Mindfulness-Based Stress Reduction. This study enrolled one-hundred and thirty-six heterogeneous subjects in an eight week MBSR program. It consisted of weekly 2.5 hour group sessions and a full day intensive meditation retreat held in the sixth week of the program. The results of the study indicated that subjects experienced significant reduction in psychological distress as shown by changes in the SCL-90-R. The follow up results, indicated that these results were maintained. Once again, even though the outcomes of the study look promising, we can not draw conclusions linking the same effects with yoga practice (Brainard et al., 2001).
Image 3: (www.rapunzelgifts.com/Yogawear.html)
It is apparent after looking at web-based and scientific study research that the effects of yoga practice on stress reduction may not be as not as clear cut as it might seem. Many advocates and companies that support and promote yoga practice make this claim routinely without hesitation, but it appears they have little scientific data to back up their statements. While the studies that have been scientifically conducted do offer some promising results, one common drawback is most are using self-report measures to assess stress levels. Studies and claims would be much more credible if physiological measures, such as hormonal, heart rate, and blood pressure levels, were incorporated or offered more concrete data to support the self-report findings. Stress becomes a much more subjective phenomena when assessed by just asking people how stressed they feel. One positive thing that seems to be arising from these studies is the fact that the negative side effects of yoga practice are minimal. Therefore, if yoga practice seems to help some people with their stress levels, it does not appear that regular practice will harm them in any way. While there is some data that lends itself to the scientific testing of yoga practice on stress levels, experimenters have barely scratched the surface. Essentially, this research shows the possibility of promising outcomes, but numerous more controlled, scientific studies will be needed to establish any sort of causal relationship.
Angen, M., Carlson, L.E., Goodey, E., Speca, M. (2000). A randomized, wait-list controlled clinical trial: The effect of a mindfulness meditation-based stress reduction program on mood and symptoms of stress in cancer outpatients. Psycosomatic Medicine, 62, 613-622.
Brainard, G.C., Greeson, J.M., Reibel, D.K., Rosenzweig, S. (2001). Mindfulness-based stress reduction and health-related quality of life in a heterogeneous patient population. General Hospital Psychiatry, 23, 183-192.
Carlson, L.E., Goodey, E., Patel, K.D., Speca, M. (2002). Mindfulness-based stress reduction in relation to quality of life, mood, symptoms of stress and levels of cortisol, dehydroepiandrosterone sulfate (DHEAS) and melatonin in breast cancer and prostate cancer patients. Psychoneuroendocrinology, 29, 448-474.
Eckert, K., Hancock, H., Mortimer, J.B., Smith, C. (2007). A randomized comparative trial of yoga and relaxation to reduce stress and anxiety. Complementary Therapies in Medicine, 15, 77-83.
Flegal, K., Kishiyama, S., Oken, B.S., Zajdal, D., et al. (2006). Randomized, controlled, six month trial of yoga in healthy seniors: effects on cognition and quality of life. Alternative Therapies in Health and Medicine, 12, 40-48.
Image 2: www.yoga.net.au/asana
Image 3: www.rapunzelgifts.com/Yogawear.html
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