INDIAN PSYCHOSOCIAL FOUNDATION
 
   INDIAN PSYCHOSOCIAL FOUNDATION
         
IJPS >
IJPS April 2011
IJPS October 2011
IJPS April 2012
IJPS October 2012
IJPS April 2013
IJPS October 2013
IJPS Apirl 2014
IJPS October 2014
IJPS Apirl 2015
IJPS Apirl 2016
IJPS October 2016
IJPS Apirl 2017
 
 
 
Comparative effect of yoga and p

Comparative effect of yoga and physical exercises on psycho-physiological parameters during examination stress in female medical students.

Vivek K Sharma1 , Ajay Kukreja2, Senthil Kumar3 S, Shailesh Gupta4, Shobha Das 5 ,M Khullar6, Lajpat Rai7 , Sarita Kanojia8

1Assistant Professor, Dept of Physiology, JIPMER, Puducherry, India

2Associate Professor & Head, Dept of Physiology, ESI Dental College, New Delhi

3 Senior Resident, Dept of Physiology, JIPMER, Puduchery

4Assistant Professor, Dept of Physiology, IMS, Banaras Hindu University, Varanasi, U.P.

5Director-Professor and Head, Dept of Physiology, V.M.M. College & S. J. Hospital, New Delhi

6Former Professor, Dept of Physiology, V.M.M. College & S.J. Hospital, New Delhi

7Former Head, Dept of Physiology, MDNIY, New Delhi

8 Assistant  Professor, Dept of Physiology, ESI Dental College, New Delhi

Abstract

 

Background:It’s a known fact with duration stipulation; the amount of stress incurred is amongst the highest in the medical students. The congenial expertise in stress management programmed can help them to cope with stress better.

Aim: Present study is to evaluate and compare the differential effects of yoga and physical exercise on psycho-physiological parameters in young female medical students.

Methodology: The study was carried out on 60 first-year MBBS students who were assigned to yoga group (Group 1) and physical exercise group (Group 2) (30 each). Group 1 underwent yoga practices and Group 2 underwent exercise in bicycle ergo meter for 40 minutes daily for twelve weeks. Physiological parameters like heart rate, respiratory rate, and blood pressure were measured. Maudsley Personality Inventory (MPI) was used to assess the neuroticism and extroversion traits of a person. Inventories developed by Defense Institute for Physiology & Applied Sciences (DIPAS) were used to measure traits of anger and type of personality.

Result: In our study, it was observed that there was no significant rise in pulse rate of Group 1 subjects, there was significant increase in pulse rate (p < 0.05) in Group 2 subjects at stressor 1 (p< 0.05) which again became non-significant at stressor 2 compared to their baseline level. There was no change in neuroticism scores in Group 1 subjects but there was a significant increase in Group 2. Further, there was highly significant (p<0.001) increase in extraversion scores of Group 1 subjects both at stressor 1and stressor 2 whereas, significant increase in extraversion scores in Group 2 subjects was seen only at stressor 2 (p < 0.05).There was more significant decrease in anger score in Group 1 subjects (p < 0.001) as compared to Group 2 subjects (p <0.01). There was significant change in personality trait from Type A towards Type B in both group subjects (p < 0.05) at stressor 1 and stressor 2 (p < 0.001).

Conclusion:Both forms of intervention i.e. yoga training and physical exercises are beneficial for the subjects in reducing the effect of examination stress on tested psycho-physiological parameters but effect of yoga practice starts immediately and is more pronounced.

 

Keywords: Yoga, Exercise, Psycho physiological parameters, Stress, Medical students

 

Introduction

Stress can be considered as a state of mental or emotional strain or tension resulting from adverse or demanding circumstances. American institute of stress defines stress as a condition or feeling experienced when a person perceives that demands exceed the personal and social resources the individual is able to mobilize. The stressful condition of students taking examination can be considered as a good model of naturalistic stress in human beings as compared with laboratory-induced stress situations. Medical education is well known to be highly competitive in nature and previous studies have already documented that perceived stress scores are higher in medical students as compared to other students in the same age group 1;2. Previous studies indicate that stress is more during examinations 3 and it level is higher in the female students compared to the male students 4.Stress management programmes for medical students have shown to decrease depression, anxiety and help them to use positive coping skills 5. Several stress management programs, e.g., meditation, yoga, hypnosis, imagery, muscle relaxation, have been introduced in the past. Exercise is considered as an acceptable method for improving and maintaining physical and emotional health. Yoga is an ancient science established in India, which gives the practitioner not only a healthy body but also a sound mind. A growing body of evidence supports the belief that yoga benefits physical and mental health via down-regulation of the hypothalamic–pituitary–adrenal (HPA) axis and the sympathetic nervous system (SNS) 6. Malathi et al have reported that there is significant reduction in examination stress with better academic performance and sense of wellbeing in students who practiced yoga 7. The studies comparing the effects of yoga and exercise seem to indicate that, in both healthy and diseased populations, yoga may be as effective as or better than exercise at improving a variety of health-related outcome measures 6. Hence we have proposed to study and compare the effects of yoga and physical exercise on psycho-physiological parameters in young female medical students.

 

Material and method

This study is collaborative work between Department of Physiology, Lady Hardinge Medical College and Smt. SuchetaKriplani Hospital, New Delhi (LHMC & SSKH) and Department of Physiology, Murarji Desai National Institute of Yoga (MDNIY), New Delhi.

 

Study Design

Prior permission for the present project was taken from the institutional ethical committee. Lady Hardingemedical College offers MBBS course only for girl candidates, hence, only female subjects in the age group of 17-20 years were selected for the present study. After meeting inclusion and exclusion criteria of the study, consecutive, consorting 60 first year MBBS female student volunteers were selected and enrolled into the study. It is a non-randomized trial. Based on their preference for yogic training or physical exercise, students were divided into two groups as follows:

Group1 (n=30): subjects who underwent yoga training

Group 2 (n=30): subjects who practiced physical exercises on stationary bicylcle

 

Inclusion Criteria:

·         Healthy female subjects in the age group of 17-20 years.

 

Exclusion Criteria:

·         Subjects who have practiced any other yogic exercises including meditation or biofeedback relaxation technique in past one year

·         Subjects with history of previous or current organic diseases.

·         Subjects who have participated in athletic events in past one year

 

Intervention for both the groups (i.e. yogic exercises for Group 1 subjects and physical exercises for Group 2 subjects) was given for 40 minutes daily, six times per week for the duration of 12 weeks. All subjects were assessed thrice during the study as follows:

1.       Baseline recordings when no examination stress was given (No stress)

2.       6 weeks later formative assessment examination was conducted and recordings were taken just before the examination (Stressor 1)

3.       12 weeks later, another formative examination was conducted and recordings were taken just before the examination (Stressor 2)

Yoga training: To ensure regularity and uniformity, yoga training was given by qualified yoga trainer. Before the beginning of yogic training, yoga trainer familiarized Group 1 subjects with different theoretical aspects of yogic practices and technique of meditation was taught in a series of 5 lectures. Following yogic techniques were daily practiced by the Group 1 subjects:

SukshmaVyayam (micro exercises) 3 minutes

·         SthulaVyayama (gross exercises) 3 minutes

·         Pranayama 5 minutes

·         Nadi shodhana

·         Bhramari

·         Asanas (postures): 20 minutes

·         Surya namaskar

·         Urdhvahastottasana

·         Katichakrasana

·         Konasana

·         Paschimottanasana

·         Vajrasana

·         Mandookasana

·         Gaumukhasana

·         Ardhamatsyendrasana

·         Padmasana

·         Dhanurasana

·         Bhujangasana

·         Shavasana: 2 minutes

·         Dhyana (meditation) 7 minutes

·          “Om” chanting

·         Rajyoga

 

Physical exercises: Group 2 subjects were administered exercises as follows:

·         Stretching exercises: 5 minutes

·         Initially subjects started warm up on exercises on stationary bicycle for 5 minutes at the initial load of 20 watts and then exercised at moderate intensity level exercise on computerized bicycle ergo meter (ergo line 900 supplied by Jaeger, Germany) for next 20 minutes which was again followed by pedalling at 20 watts load as cool down. Subjects were asked to maintain target heart rate between 55-75 % of maximum heart rate (HRmax) calculated by formula HRmax = 220-age (years) for 20 minutes.

·         Afterwards, students again did 5 minutes of stretching exercises.

All the subjects (n=60) were asked to present on the day of assessment between 9 AM to 11 AM at least 2 hours after taking light breakfast to the department of Physiology, LHMC and written informed consent was taken from them. All the subjects were then assessed on following tests:

 

Physiological Parameters:

1.       Basal pulse rate and blood pressure

2.       Respiratory rate  (BPM)

3.       Psychological tests

a.       Maudsley Personality Inventory (MPI)8 is a commonly used questionnaire to assess the personality traits of a person. It consists of 48 questions and it assesses personality on two biologically-based independent dimensions of temperament measured on a continuum as follows:

·         Neuroticism / Stability: Neuroticism or emotionality is characterized by high levels of negative affect as compared to normal healthy subjects. According to Eysenck’s theory; neuroticism is based on activation thresholds in the sympathetic nervous system or visceral brain. This is the part of the brain that is responsible for the fight-or-flight response in the face of danger. Neurotic people have lower activation thresholds, therefore find it difficult to control their emotional reactions, experience negative affect (fight or flight) and become nervous or get upset in the event of even minor stressors. If individual is emotionally stable, he can handle pressure better and remains calm even under stressful conditions.

·         Extraversion is characterized by being outgoing, talkative, high on positive affect (feeling good), and in need of external stimulation as opposed to introversion with opposite characteristics. According to Eysenck’s arousal theory, optimum performance of individual is based on adequate cortical arousal. Introverts have higher arousal and therefore are seeking peace and aloofness as compared to extroverts who are under-aroused and need external stimulation for enhancing performance. Within limits (scores from 30 to 70), increase in extraversion scores can be depicted as positive, emotionally stable and cheerful state. Above or below these scores indicates considerable deviation from the average healthy mental condition.

b.       Inventories developed by Defense nstitute for Physiology & Applied Sciences (DIPAS) were used to measure traits of anger and type of personality. These inventories are chosen because they are valid for Indian population, reliable and specific to measure the tested psychological domains. Every item amongst all the questionnaires measures the tested domain on the weighted scores of responses from 0 to 3 ranging from ‘never’ to ‘almost always’ response respectively. Questionnaires were scored by adding the weighted (0 to 3) scores of each item. Following Psychological inventories were used:

Personality Type A / B: It consists of 17 questions and aims to assess the attitudes and interests of individual. Optimal score is less than 20. Higher score represents individual having more type A personality characteristics as compared to type B personality characteristics. This scale was chosen because MBBS course is highly competitive and students with type A personality characteristics are exposed more to stress and have higher chance of suffering from a physical or mental disorder on account of the pressure of stressful events. Type A personality is characterized by more aggressiveness, impatience and intolerance towards others, high ambitiousness, strong need to always have situations totally under control, strong drive to acquire things, objects and assets and to be a consumer, addictive behaviour with very limited physical activity, few interests apart from work and irregular and excessive eating habits. On the other hand, type-B category reveals a greater capacity to cope with potentially stressful situations, consequently reducing their risk of becoming ill. The difference between the two types does not depend on the fact they present two different and well-defined

personality structures but rather on the way in which they organize their responses to stressful situations.

Anger self report scale: Anger, hostility and aggression are central concepts of many theories of personality. Perceived stress levels have been reported to be higher in medical students. This scale consists of 16 items and was included because it was hypothesized that chronic high levels of stress may lead to increased levels of anger related behaviour. Maladaptive effects of anger and hostility can make individual prone to hypertension, depression, anxiety and other psychiatric disorders. This scale rates individual on the level of angry feelings and expression of anger reactions (general, physical and verbal), guilt and hostility self-directed (intropunitive ness) or towards other people or objects (extra punitive ness).Optimal score is < 6

 

Result

Table 1 shows the comparison of baseline levels of tested physiological and psychological parameters between subjects of both the groups. There is no significant difference between the groups except for extraversion score (p<0.05). Hence, groups can be considered comparable for the study.


Table 1:  Comparison of basal parameters

Parameter

Group 1

Group 2

P value

Neuroticism

53.83±5.48

52.53±5.31

0.3546

Extraversion

33.36±6.74

39.76±8.22*

0.0017

Personality

25.73±3.51

26.66±2.96

0.2718

Anger

22.06±4.55

21.00±6.46

0.4654

Anxiety

48.48±5.64

51.20±7.45

0.1163

Pulse Rate

77.00±3.72

76.60±3.79

0.6815

Respiratory Rate

17.30±3.14

17.20±2.72

0.8956

Systolic Blood pressure

104.73±5.26

103.93±5.25

0.5577

Diastolic Blood Pressure

68.57±4.61

67.53±3.88

0.3484

Mean Arterial Pressure

80.62±3.65

79.67±2.89

0.2683

Rate Pressure Product

80.69±6.25

79.69±6.68

0.5517

p<0.05: significant


 


Table 2 Shows the changes occurring in all the tested physiological and psychological parameters in both the groups from baseline level to stressor 1 and stressor 2 and also compares the differences obtained between group 1 subjects and group 2 subjects at stressor 1 and stressor 2. Results are explained later in discussion.


Table 2: Comparison of basal parameters with examination stress in yoga and physical education group

Parameters

group

Basal

Examination stress 1

Examination stress 2

Neuroticism

Yoga

53.83±5.48

54.73±5.97

54.40±6.13

Physical group

52.53±5.31

54.60±3.78*

55.13±3.83**

Extraversion

Yoga

33.36±6.74

37.60±5.81***

40.03±5.75***##

Physical group

39.76±8.22

42.50±7.45

43.16±6.02*

Personality

Yoga

25.73±3.51

24.40±4.16*

23.66±4.16***

Physical group

26.66±2.96

25.06±3.45*

24.23±3.34***

Anger

Yoga

22.06±4.5

18.10±6.46***

16.41±9.37***

Physical group

21.00±6.46

17.00±6.68***

17.43±6.90**

Pulse Rate

Yoga

76.53±4.83

76.57±4.03

73.67±4.25

Physical group

76.33±3.5

78.50±3.9*

76.80±3.04

Respiratory Rate

Yoga

17.30±3.14

16.93±2.79

16.07±3.68

Physical group

17.20±2.72

17.07±3.04

16.83±2.53

Systolic Blood pressure

Yoga

114.73±5.26

113.73±5.26

112.23±4.79

Physical group

113.93±5.25

113.07±5.09

112.10±5.30

Diastolic Blood Pressure

Yoga

68.57±4.61

68.03±4.85

66.73±3.87

Physical group

67.53±3.88

66.87±3.81

66.90±3.59

Mean Arterial Pressure

Yoga

83.96±3.65

83.27±3.77

81.90±3.29

Physical group

83.00±2.89

82.27±3.13

81.97±2.78

Rate Pressure product

Yoga

87.89±7.70

87.13±6.71

82.74±6.66

Physical group

87.07±7.52

87.27±6.29

86.14±6.10

*Compared with basal value*<0.05,**<0.01,***<0.001, #Compared with 6 weeks value#<0.05,##<0.01,###<0.001


Discussion

Table 1 shows that baselines of two groups were well matched for all the tested physiological and psychological parameters except for the higher baseline extraversion scores in Group 1 subjects as compared to Group 2 subjects (p < 0.01). Therefore, both groups can be considered comparable for the study. In our study, it was observed that there was no significant rise in pulse rate of Group 1 subjects, both at stressor 1 (examination stress at 6 weeks) and at stressor 2 (examination stress at 12 weeks) as compared to baseline (no stressor) whereas, there was significant increase in pulse rate (p < 0.05) in Group 2 subjects at stressor 1 (p< 0.05) which again became non-significant at stressor 2 compared to their baseline level. Stress induces imbalance of the autonomic nervous system (ANS) with decreased parasympathetic nervous system (PNS) and increased sympathetic nervous system (SNS) activity9.This demonstrates that both interventions i.e. yoga training and physical exercises for 12 weeks can lead to reduction of stress levels and thereby, preventing the autonomic deregulation by stressor but the effect of yoga practice on autonomic tone stabilization starts much before physical exercises. Also, there was no significant change in both the groups on other tested physiological parameters at both stressors as compared to their baseline. Results of Group 1 subjects are similar to findings observed by previous study by Gopal et al who studied the effect of examination stress on young female subjects after 12 weeks of yoga practice and compared it with control subjects10.There was no significant rise in the heart rate of subjects practicing yoga for 12 weeks as compared to group 2 subjects who showed significant rise in heart rate during examination stress. Result of Group 2 subjects are in agreement with previous studies which documented that long term moderate intensity aerobic exercise training causes increased parasympathetic activity and therefore improves the autonomic tone of the subjects11.Therefore; our study demonstrates that yoga training was more effective than physical exercise in stabilizing autonomic tone of the subjects exposed to examination stress.

In this study, we also found that there was no change in neuroticism scores in Group 1 subjects both at stressor 1 (at 6 weeks) and stressor 2 (12 weeks), whereas, there was significant increase in neuroticism scores in Group 2 subjects at stressor 1 (p < 0.05) and 2 (p < 0.01) as compared to their baseline values. Further, there was highly significant increase in extraversion scores of Group 1 subjects both at stressor 1 (p < 0.001) and stressor 2 (p < 0.001) with continued improvement in scores from 6 to 12 weeks of intervention (p< 0. 001) whereas, significant increase in extraversion scores in Group 2 subjects was seen only at stressor 2 (p< 0.05). Again, this demonstrates that effect of yoga training starts earlier and has higher impact as compared to physical exercise. Our results are similar to findings obtained by Udupa & Singh who found 12 weeks of hatha yoga training results in decreased neuroticism and decreased mental fatigability12. Other studies also found yoga suitable in the treatment of neurosis and neurotic behavior arising out of stressful life events13.

There was significant decrease in anger score in both Group 1 (p < 0.001) and Group 2 subjects (p < 0.001) at stressor 1. However, there was more significant decrease in anger score in Group 1 subjects (p < 0.001) as compared to Group 2 subjects (p <0.01).Our results are consistent with previous study which found that there is significant and comparable improvement in mood including reduction in anger scores, tension and fatigue level of subjects doing either yoga training or physical exercises14;15.Therefore, results of our study show that subject practicing either regular yoga training or physical exercises for 12 weeks is better able to control his negative emotions like anger and hostility towards stressor as compared to sedentary individual.

There was significant change in personality trait from Type A towards Type B in both group subjects (p < 0.05) at stressor 1 and stressor 2 (p < 0.001). This observation is in concordance with previous studies stating that yoga tends to make individuals more relaxed and calm and has preventive role in ‘burnout syndrome’, a trait characteristic of type A personality individual13. Similar changes of conversion of type A personality to type B by yoga practice have been also been previously observed in school children16.

Therefore, our study concludes that both yoga training and physical exercises are beneficial for the subjects, however, the effects of yoga training start earlier and have comparatively more impact on measured psycho-physiological parameters as compared to physical exercise. In a previous study, Ross et al also concluded yoga may be as effective as or better than exercise at improving a variety of health-related outcome measures. Differences that have been found between yoga and exercise training may be a result of how the two interventions differ in their effects upon the autonomic tone and HPA axis. Different levels of intensity of exercise have been shown to affect the HPA axis response to acute stress differently6. Low-intensity exercise repeatedly has been shown to decrease HPA axis lower cortisol levels17;18and while higher intensity exercise leads to proportional increases in cortisol19.Exercise stimulates SNS, raising plasma catecholamines20;21 whereas, yoga has been shown to lower SNS and therefore, reduces catecholamine level22. When a sedentary subject starts practicing moderate intensity physical exercise, it causes stimulation of sympathetic nervous system (SNS), raising plasma epinephrine and nor epinephrine. If physical exercises continued for longer time, tread to better autonomic tone and HPA axis regulation.

Yogasanas are low intensity usually non-strenuous exercises which affect HPA axis positively bringing down sympathetic stimulation and significantly decreasing the release of catecholamine. Also, yoga-based practices have been found to correct under activity of the parasympathetic nervous system (PNS) and GABA systems in part through stimulation of the vagus nerves, the main peripheral pathway of the PNS9.As integrated yoga practice includes aspects of exercise (asana), breath manipulation (pranayama) and relaxation (meditation), effects of yoga are multi-dimensional and have immediate down-regulating effect on both SNS / HPA axis response to stress6. Regular practice of meditation has also been documented to reduce sympathetic activity, balance neuro-endocrine axis and decrease stress and anxiety levels23;24.

 

Conclusion

Our study demonstrates that both forms of intervention i.e. yoga training and physical exercises are beneficial for the subjects in reducing the effect of examination stress on tested psycho-physiological parameters but effect of yoga practice starts immediately and is more pronounced on most of the tested parameters. Yoga is a form of low intensity exercise affecting HPA axis positively and reducing the autonomic dysregulation caused by examination stress where as, moderate intensity physical exercises initially stimulates HPA axis and SNS but ultimately also improves autonomic tone with longer duration of practice.

 

Limitations of study: 

It is a non-randomized trial and results should be interpreted with potential rater bias. Other forms of physical exercises could not be included.

 

References

1.        Dahlin M, Joneborg N, Runeson B. Stress and depression among medical students: a cross-sectional study. Med Educ 2005;39:594-604.

2.        Zoccolillo M, Murphy GE, Wetzel RD. Depression among medical students. J Affect Disord 1986;11:91-96.

3.        Aarti Sood Mahajan. Stress in Medical Education: a global issue or Much Ado About Nothing specific? South-East Asian Journal of Medical Education2010;4:9-13.

4.        Abdulghani HM, AlKanhal AA, Mahmoud ES, Ponnamperuma GG, Alfaris EA. Stress and its effects on medical students: a cross-sectional study at a college of medicine in Saudi Arabia. J Health Popul Nutr 2011;29:516-522.

5.        Shapiro SL, Shapiro DE, Schwartz GE. Stress management in medical education: a review of the literature. Acad Med 2000;75:748-759.

6.        Ross A, Thomas S. The health benefits of yoga and exercise: a review of comparison studies. J Altern Complement Med 2010;16:3-12.

7.        Malathi A, Damodaran A. Stress due to exams in medical students--role of yoga. Indian J Physiol Pharmacol 1999;43:218-224.

8.        Eyesenck H.J. The questionnaire measurement of neuroticisma and extraversion. Riv Di Psicologia 1950;50:113-140.

9.        Streeter CC, Gerbarg PL, Saper RB, Ciraulo DA, Brown RP. Effects of yoga on the autonomic nervous system, gamma-aminobutyric-acid, and allostasis in epilepsy, depression, and post-traumatic stress disorder. Med Hypotheses 2012;78:571-579.

10.     Gopal A, Mondal S, Gandhi A, Arora S, Bhattacharjee J. Effect of integrated yoga practices on immune responses in examination stress - A preliminary study. Int J Yoga 2011;4:26-32.

11.     Raczak G, Danilowicz-Szymanowicz L, Kobuszewska-Chwirot M, Ratkowski W, Figura-Chmielewska M, Szwoch M. Long-term exercise training improves autonomic nervous system profile in professional runners. Kardiol Pol 2006;64:135-140.

12.     Udupa KN, Singh RH. The scientific basis of yoga. JAMA 1972;220:1365.

13.     Nespor K. [Use of yoga in psychiatry]. Cas Lek Cesk 1994;133:295-297.

14.     Hassmen P, Koivula N, Uutela A. Physical exercise and psychological well-being: a population study in Finland. Prev Med 2000;30:17-25.

15.     Dua JK, Swinden ML. Effectiveness of negative-thought-reduction, meditation and placebo training treatment in reducing anger. Scand J Psychol1992;33:135-146.

16.     Lajpat Rai, H.N.Chaudry, CHS Shastry. The effect of administraton of yogic education programme on relationship between Emotional and Social Behaviour in school children. Indian J Physiol Pharmacol 1992;36:77-82.

17.     Few JD. Effect of exercise on the secretion and metabolism of cortisol in man. Journal of Endocrinology 1974;62:341-353.

18.     Davies CT, FEW JD. Effects of exercise on adrenocortical function. Journal of Applied Physiology 1973;35:887-891.

19.     Howlett TA. Hormonal responses to exercise and training: a short review. Clin Endocrinol (Oxf) 1987;26:723-742.

20.     Peronnet F, Cleroux J, Perrault H, Cousineau D, de Champlain J, Nadeau R. Plasma norepinephrine response to exercise before and after training in humans. Journal of Applied Physiology 1981;51:812-815.

21.     Bloom SR, Johnson RH, Park DM, Rennie MJ, Sulaiman WR. Differences in the metabolic and hormonal response to exercise between racing cyclists and untrained individuals. J Physiol 1976;258:1-18.

22.     Selvamurthy W, Sridharan K, Ray US et al. A new physiological approach to control essential hypertension. Indian J Physiol Pharmacol 1998;42:205-213.

23.     Vempati RP, Telles S. Yoga-Based guided relaxation reduces sympathetic activity judged from baseline levels. Psychological Reports 2002;90:487-494.

24.     Lee SH, Ahn SC, Lee YJ, Choi TK, Yook KH, Suh SY. Effectiveness of a meditation-based stress management program as an adjunct to pharmacotherapy in patients with anxiety disorder [abstract]Lee SH, Ahn SC, Lee YJ, Choi TK, Yook KH, Suh SY. J Psychosom Res 2007;62:189-195