A Study On Yoga Nidra In Stress And Heart Disease

Extracts from Stress and Heart Disease by Hon. Brig. K.K. Datey and S.S. Bhagal. Quarterly Journal of Surgical Sciences, Vol. 13, Nos. 3-4 September-December 1977.

This study was undertaken to find out the effect of relaxation techniques, biofeedback training and shavasana (a yogic exercise) in patients suffering from hypertension.

Material and methods

Twenty-seven patients of hypertension were taken up for biofeedback training and 86 for shavasana.

Biofeedback groups

This group consisted of 27 patients, 16 males and 11 females. Their ages ranged from 39 to 78 years (average 55). They were known to be hypertensive for at least one year and in some cases, as long as 20 years (average 6.8 years). The etiology of hypertension was essential in 25 and renal in 2. All except 2 were taking anti-hypertensive drugs but their blood pressure was not controlled adequately. Twenty hypertensive controls, 9 males and 11 females, were matched from an age and sex register as closely as possible to the treated group. In this group 18 patients had essential and a renal hypertension. The average blood pressure in both groups of patients is shown in Table 1.

Table 1 - Average blood pressure in treated and control groups
    Blood Pressure
Group Average Age Original Systolic & Diastolic Pretrial Systolic & Diastolic Mean Original Mean Pretrial
Treated 55 168/105 157/98 126 118
Control 57 170/108 166/100 128 122

The original pressure is the one recorded when the subject was first detected to be hypertensive. The pre-trial baseline blood pressure is an average of 18 readings taken over 3 separate days after half an hour's rest on each day. Blood pressure was taken in the standing, sitting and supine positions and their average taken as the final reading. Similar criteria applied to the control group.

Symptoms of these patients varied. In order of their frequency, they were tiredness, headache, dyspnea on exertion, dizziness, irritability, chest pain with or without angina, palpitation, nervousness and depression. Headache and tiredness were very common and were present in 70% and 65% of the patients respectively. The symptoms in the treated and control groups were comparable.


All patients were appropriately motivated to get their maximum co-operation. They were seen individually three times a week for a half-an-hour session for an average of 9 weeks. Their blood pressures were recorded in the standing, sitting and supine positions at the beginning and again at the end of each session. An ordinary mercury sphygmomanometer was used. This was checked frequently for accuracy. All diastolic pressures were taken in the 5th phase. These patients were given training in relaxation and biofeedback methods. The patients in the control group also attended 3 times a week for 9 weeks. Their blood pressure was taken on arrival and again after half-an-hour's rest on a couch. They were neither instructed in relaxation nor told of their blood pressure levels and they were not connected to any biofeedback instruments.

The training sessions were carried out in a room at a comfortable temperature. External noise was kept to a minimum but no attempts were made to make the room soundproof. No meals were taken for one hour beforehand. Tight clothes and glasses were removed.

During the training session, the patient lay on an examination couch fully relaxed. The eyes were kept closed. The patient was at first asked to breathe slowly and rhythmically, allowing the rhythm to take its effortless and natural pace.

During the whole session, the patient was connected to a biofeedback apparatus depicting galvanic skin resistance (GSR) by means of a continuous sound signal. Changes in skin resistance provide a fairly reliable measure of the degree of relaxation. The cause of changes in skin resistance is not completely known, but sweat gland activity, which is proportional to the activity of the sympathetic nervous system, is one of the factors concerned. As relaxation progresses the skin resistance increases and a drop occurs in the pitch of the audio signal. Thus a correct response is immediately reinforced, encouraging the patient to continue efforts in the right direction.

At the end of a session, each patient was told his blood pressure level before and after the session. Patients were encouraged to practise relaxation at home twice a day. The dosage of drugs was adjusted according to the response and the patient actively participated in this decision of dosage adjustment.

Shavasana group

This group consisted of 68 male patients and 18 females. Their ages varied from 22 to 64 years with an average of 40 years. Their original systolic blood pressure ranged from 160-270mm. Hg and diastolic from 90-145mm. Hg. The average blood pressure was 186/115mm. Hg The aetiology of hypertension was essential in 62, renal in 19 and arteriosclerotic in 5. These patients were divided into three groups as shown in Table 2.

Table 2 - Total number of patients in shavasana group- 86 patients divided into 3 groups
Number of patients/Etiology of hypertension
Group Essential Renal Arterio-sclerotic Total
1 No drugs 8 4 3 15
2 B.P. adequately controlled with drugs 36 7 2 45
3 BP inadequately controlled in spite of drugs 18 8   26
Total 162 19 5 86

Group 1 consisted of 15 patients of hypertension. This group had not received any antihypertensive drugs. They were given placebo tablets for 1 month before teaching them shavasana.

Group 2 consisted of 45 patients. These patients were on antihypertensive drugs for at least 2 years and their blood pressure was adequately controlled.

Group 3 consisted of 26 patients. These patients were on antihypertensive drugs but their blood pressure was not adequately controlled.

The blood pressure of patients not receiving antihypertensive drugs was recorded in the recumbent and upright positions and there was no postural hypotension. However, in those on antihypertensive drugs, it was recorded in three positions; recumbent, sitting and upright. The mean blood pressure was calculated as the diastolic blood pressure plus one-third the pulse pressure. The average mean blood pressure in the recumbent position in group 1 and the average of the mean blood pressures in all the three positions of groups 2 and 3 are shown in Table 3.

Table 3 - The average mean blood pressure of the three shavasana groups. *BP recorded when the subject was first detected to be hypertensive. **BP recorded after giving drugs or placebo but before starting shavasana.
Group Mean blood pressure (original) before any therapy* (mm. Hg) Initial mean blood pressure** with placebo or drugs
1 136 Placebo 134
2 137 Drugs 102
3 147 Drugs 120

The symptoms in the patients were giddiness, headache, palpitation, breathlessness, angina, irritability, insomnia, nervousness and exhaustion.

All the investigations were carried out in these patients before the commencement of shavasana, and at regular intervals thereafter. Electromyogram of the frontalis muscle was recorded before as well as during the exercise in some patients to confirm the muscular relaxation during the exercise.

These investigations were repeated periodically. Patients were instructed to attend the Cardiac Centre every day to learn the exercise; once they had learned it correctly, they were advised to attend weekly to check their blood pressure and the correct technique of the exercise.

Technique of yogic exercise (shavasana)

The patient was allowed a light breakfast an hour before the exercise. He wore light and loose clothes while performing the exercise, which was performed as follows:

The patient lies in the supine position, lower limbs 30 degrees apart and the upper limbs making an angle of 15 degrees with the trunk, with the forearms in the mid-prone position and fingers semi-flexed. The eyes are closed with eyelids drooping. The patient is taught slow, rhythmic diaphragmatic breathing with a short pause after each inspiration and a longer one at the end of each expiration. After establishing this rhythm, he is asked to attend to the sensation at the nostrils, the coolness of the inspired air and the warmth of the expired air. This procedure helps to keep the patient inwardly alert and to forget his usual thoughts, thus becoming less conscious of the external environment, thereby attaining relaxation. The patient is asked to relax the muscles so that he is able to feel the heaviness of different parts of the body. This is achieved automatically once the patient learns the exercise. The exercise is performed for 30 minutes. An experienced supervisor checks that there is no movement of any part of the body, except rhythmic abdominal movements. Physical relaxation is checked from time to time by lifting the extremities and letting them go to observe their flaccidity. Most of the patients learn the exercise correctly in about 3 weeks. The pulse, blood pressure and respiration are recorded before and after the exercise. After patients learn the exercise correctly, the respiratory rate is usually between 4-10 per minute.

The dosage of drugs in patients of groups 2 and 3 was adjusted according to the response. The percentage of reduction of drugs was calculated in each case from the original drug requirement before starting shavasana.


Subjective improvement was seen in the majority of patients in both the groups. Symptoms like headache, giddiness, nervousness, irritability and insomnia disappeared in most patients and there was a sense of well-being.

Biofeedback group

There was a significant reduction in blood pressure in the treated group as compared to the control group. 21 patients out of 27 showed significant reduction in blood pressure. The average mean blood pressure reduced from 118 to 103mm. Hg. After 4 months follow up, it was 107mm. Hg. In about 50% of patients the drug requirement was reduced from 33 to 100% (average 41%). There was no significant change in blood pressure of patients in the control group.

Shavasana group

A fall of blood pressure was noted in all the three groups. In patients of group 1 the average mean blood pressure came down from 134 to 107mm. Hg. (a fall of 27mm. Hg). The results are shown in Table 4.

Table 4 - Objective improvement in 15 patients without drugs. *p less than 0.05
Mean Blood Pressure Average mm. Hg Initial mean
Initial mean 134
After shavasana 107*
Reduction 27

In group 2 the fall in blood pressure was from 102 to 100 mm. Hg but the drug requirement was reduced to 32% of the original in 27 patients (60%). In group 3 the average blood pressure dropped from 120 to no mm. Hg and the drug requirement was reduced to 29% of the original in 10 patients (38%). These results are shown in Table 5.

Table 5 - Objective improvement in groups 2 and 3 (17 patients on drugs). *p less than 0.05
Group and no. of patients Average initial mean blood pressure Average mean blood pressure after shavasana Drug requirement
2(45) 102 mm. Hg 100 110 32% in 27 (60%)*
3(26) 120 mm. Hg 100 110 29% in 10 (38%)

From these results it is clear that relaxation techniques like biofeedback training and shavasana help in reduction of blood pressure in hypertensive patients.


The hypothalamus is a control station of the autonomic nervous system and maintains homeostasis. The resulting hemodynamic changes in essential hypertension are similar to those occurring in a normotensive person during emotional stress. These changes can also be produced by direct electrical stimulation of motor centres and regions of the hypothalamus. It appears that repeated hypothalamic stimulation leads to sustained high blood pressure. Several papers in the literature have indicated that psychological stress plays an important part in the pathogenesis of hypertension.

Whatever the aetiology of hypertension, there is pari passu, a rise in the level at which the homeostatic mechanisms operate and these react against both rise and fall of blood pressure. Thus the regulatory mechanism in the hypothalamus is probably set at a higher level in hypertension, and if it can be reset at the normal level, the hypertension may be controlled.

Normally the cerebral cortex receives a wide variety of messages from the environment leading to an emotional and mental response. These messages are passed on to the limbic areas leading to hypothalamic and pituitary responses which are reflected as physiological responses, e.g. on getting a telephone call a person may start sweating, having palpitations or a rise in blood pressure.

Yoga training leads to heightened cortical arousabiltty and reduced limbic arousability at the same time, which expresses itself in human personality and subjective experience as heightened perceptual awareness and simultaneously reduced emotional reaction. Thus the regulatory mechanism in the hypothalamus is set at normal or near normal level. This helps in reducing high blood pressure. With biofeedback training, the physiological changes are perceived from moment to moment by means of instruments. This motivates the persons to modify these changes, resulting in modified hypothalamic and pituitary responses. Thus the two techniques achieve similar results though they are mediated through different neurophysiological pathways.


Man is subjected to more stress and strain in this age than ever before. Stress plays an important part in the pathogenesis of essential hypertension.

Twenty-seven patients of hypertension were given biofeedback training. Galvanic skin resistance (GSR) gave an indication of relaxation. At the end of the trial subjective improvement was noted in most of the patients. Mean B. P. was reduced from 118 to 103 mm. Hg and drug requirement to 41%. Similar results were seen with biofeedback temperature regulation.

Eighty-six patients of hypertension were taught shavasana, a yogic exercise. Patients were divided into three groups. Group 1 consisted of patients who were not taking any anti-hypertensive drugs, group 2 comprised patients whose blood pressure was adequately controlled with drugs and group 3 consisted of patients whose blood pressure was not adequately controlled in spite of drugs.

After practising shavasana, at the end of 3 months, a majority of patients reported a general feeling of well-being and marked improvement in symptoms like headache, insomnia, nervousness, etc. In group 1 there was reduction of mean B. P. from 134 to 107 mm. Hg. In group 2 the drug requirement was reduced to 32%. In group 3 mean B. P. was reduced from 120 to 110 mm. Hg and drug requirement to 29%. The mechanism of reduction of blood pressure is discussed.

Thus biofeedback training and/or shavasana are an important addition to the existing anti-hypertensive armamentaria.