Posted 04.23.2019 | by AMRA
Little is known about the impact of many years of mindfulness practice on the body’s response to stress. Robb et al. [Complementary Medicine Research] conducted a pilot study that measured salivary cortisol levels in a group of long-term mindfulness practitioners. Salivary cortisol is a biological measure that is highly reactive to stress. The researchers predicted that morning cortisol levels would be lowest for meditators with the most meditative experience.
Salivary cortisol levels typically peak during the first hour after waking up, and then decline throughout the rest of the day. Morning cortisol levels tend to be higher when under acute stress, and tend to be lower in states of exhaustion and burnout following long-term stress.
The authors recruited 83 certified Mindfulness-Based Stress Reduction (MBSR) teachers (73% female; 96% Caucasian; average age = 58; 92% with graduate degrees) to participate in the study. The participants completed an online questionnaire assessing a variety of health and lifestyle variables, perceived stress, and the extent of their meditation practice. They were then asked to produce a saliva sample upon first waking up, followed by 3 additional samples collected at 15-minute intervals. The total amount of cortisol produced during the first 45 minutes after awakening was then estimated using area under the curve (AUC) calculations.
The results showed that participants in the upper quartile of meditative experience (>26 years) had significantly higher (48%) total estimated morning cortisol amounts than those in the lowest (<10 years) quartile. The relationship between years of meditative experience and total morning cortisol remained significant when meditation experience was treated as a continuous variable.
In a closer examination of the data, this difference between participants in the upper and lower quartiles of meditative experience only remained significant when comparing the early risers (those who woke up before 6:30 AM). Highest-quartile early-risers’ cortisol levels were 202% higher than their lowest-quartile early-riser compatriots. In comparison, the highest-quartile late-risers’ cortisol levels were 40% lower than their lowest-quartile late-rising compatriots. This interaction effect between years of meditative experience and the hour participants woke up on cortisol levels fell short of statistical significance. Cortisol awakening response levels were unrelated to self-reported levels of perceived stress.
These results show that mindfulness meditators with the greatest number of practice years who wake up early have the highest total morning cortisol levels, thus contradicting the researchers’ expectations. Still, the meaning of these results is not clear. Cortisol levels are notoriously affected by many variables. It is not always evident whether higher cortisol levels indicate being more highly stressed, being less burned out, having a better adaptive response to stress, being more prepared to meet the demands of the day, or some other factor.
The researchers conclude that the results are intriguing enough to warrant further investigation. The study is limited by only measuring the cortisol awakening response and not looking at the slope of cortisol levels throughout the day. A complete daily slope might differentiate whether higher morning levels are due to increased stress or decreased burnout. Cortisol samples were obtained at home by participants which increases the possibility of collection error.
Robb, S. W., Haslam, A., Wirth, M. D., Gay, J. L., Middleton, L., Healy, M., & Hebert, J. R. (2019). Relationship between meditation and waking salivary cortisol secretion among long-term MBSR instructors. Complementary Medicine Research.