Subjective Sleep Quality and hormonal modulation in long-term yoga practitioners

Yoga represents a fascinating mind-body approach, wherein body movements (asana), breathing exercises (pranayama) and meditation are integrated into a single multidimensional practice. Numerous beneficial mental and physical effects have been classically ascribed to this holistic ancient method. The purpose of the present study has been to examine the effects of long-term yoga practice on Subjective Sleep Quality (SSQ) and on several hormonal parameters of the hypothalamus-pituitary-adrenal (HPA) axis. Twenty-six subjects (16 experimental and 10 controls) were recruited to be part of the study. Experimental subjects were regular yoga practitioners with a minimum of 3 years of practice. Blood samples for the quantification of adrenocorticotropic hormone (ACTH), cortisol and dehydroepian-drosterone sulphate (DHEA-S) were drawn from all subjects. Likewise, the Pittsburgh Sleep Quality Index (PSQI) was employed to assess SSQ. As statistical analysis, Mann-Whitney U-test was performed. The yoga group displayed lower PSQI scores and higher blood cortisol levels than control subjects. Therefore, it can be concluded that long-term yoga practice is associated with significant psycho-biological differences, including better sleep quality as well as a modulatory action on the levels of cortisol. These preliminary results suggest interesting clinical implications which should be further researched. (C) 2009 Elsevier B.V. All rights reserved.