The PTQ (Ehring et al., 2011) is a 15-item questionnaire assessing the tendency to engage in repetitive negative thinking independent of a disorder-specific content. Items are rated on a scale ranging from 0 (never) to 4 (almost always). The PTQ consists of three subscales: Core features of repetitive negative thinking, perceived unproductiveness of repetitive negative thinking , and repetitive negative thinking capturing mental capacity (sample item: 'My thoughts prevent me from focusing on other things'.). Confirmatory factor analysis provides support for a 3-factor solution. Assessment of the psychometric properties of the PTQ, including the Dutch version (Ehring, Raes, Weidacker, & Emmelkamp, 2012), has demonstrated high internal consistency (a = .93-.95), acceptable test-retest reliability (r = .69-.75), good convergent validity as well as good predictive validity in the prediction of symptom levels of anxiety and depression.

The rumination scale of the Response Style Questionnaire (RSQ; Nolen-Hoeksema, 1991; German version: Kühner, Huffziger, & Nolen-Hoeksema, 2007) was used to assess repetitive negative thinking in the form of depressive rumination. The questionnaire consists of 22 items describing the individual's response to sad or depressed mood (e.g., "Think about how passive and unmotivated you feel") that are rated on a scale from '1' (never) to '4' (always). The RSQ is regarded as the standard measure of rumination; it has been used widely in clinical as well as non-clinical populations and has demonstrated high reliability and validity (Kühner et al., 2007, Luminet, 2004 and Nolen-Hoeksema, 2004).

Aspects of Spirituality (ASP) . The ASP questionnaire was developed to measure a wide variety of vital aspects of spirituality beyond conventional conceptual boundaries in secular societies. Both expert representatives of various spiritual orientations and also atheists were asked which aspects of spirituality are relevant to them (Büssing, 2006). Identified motifs we condensed to 40 items of the Aspects of Spirituality (ASP 1.0) questionnaire (7 factors; Cronbach ́s alpha = .94) (Büssing et al., 2007) which differentiates and quantifies cognitive, emotional, intentional and action-oriented matters of theism/belief, (esoteric) transcendence, existentialism, humanism etc. The reliable and valid instrument is suited to be used in health care research (Büssing et al. 2007).

The SpREUK was developed to investigate whether or not patients with chronic diseases living in secular societies rely on spirituality as a resource to cope with illness. The SpREUK questionnaire relies on essential motifs found in counseling interviews with chronic disease patients (i.e., having trust/faith; search for a transcendent source to rely on; reflection of life and subsequent change of life and behavior). The instrument is suited to be used in health care research (A Büssing, Ostermann, & Matthiessen, 2005).

A new instrument for the measurement of exceptional experiences, which considers both frequency and individual evaluation of exceptional experiences. A principal component factor analysis extracted four factors (positive spiritual experiences, experiences of deconstruction/ ego loss, psychopathological experiences and dream-type experiences), which explain 49% of the variance. The 25-item short form of the instrument shows good psychometric properties (range for Cronbach's alpha: r = 0.67-0.89, range for test- retest reliability after 6 months r = 0.66-0.87). The instrument shows adequate discriminant and convergent validity (Sense of Coherence, Social Support, Mental Distress and Transpersonal Trust) and can discriminate between spiritual practising and non practising individuals (Kohls & Walach, 2006).

Specific mind-body-interventions (i.e., yoga, quigong, therapeutic eurythmy, mindfulness-based meditation etc.) require an active (emotional) engagement of individuals practicing it. Apart from direct physiological effects, an active emotional engagement seems to be important. This type of engagement can be conceptualized as an 'inner involvement ́ (Büssing et al. 2011). Lacking this attitude in terms of an inner resistance towards the practices may lead to reduced engagement, adherence, and thus treatment efficacy. The ICPH scale ("Inner Correspondence / Peaceful Harmony with Practices") was developed to measure this 'inner correspondence in clinical studies addressing the efficacy of mind body practices involving physical movements. While it is suitable for progressive muscle relaxation, wording needs to be adjusted for mantra meditation (Arndt Büssing, Edelhuser, Weisskircher, Fouladbakhsh, & Heusser, 2011).

Change of Cardiovagal Index (CVI), a normalized measure of heart rate variability (HRV), in stress response and relaxation response after inpatient treatment.