I want to share some ideas about yoga nidra with you because I feel that it is important that we try to understand yoga nidra in a greater perspective. Although I have been calling yoga nidra psychic sleep, I have come to believe that it is more than that.
The consciousness assumes different forms during waking, dreaming and sleeping. In the raja yoga of Patanjali we call these forms vrittis or patterns of consciousness. The formation of consciousness is called awareness. Sleep is one type of awareness; memory is another. Similarly, yoga nidra is a very important form of awareness.
In the raja yoga of Patanjali there is a state called pratyahara, when mind and mental awareness are dissociated from the sensory channels. The perfection of pratyahara leads to concentration and then to meditation. Yoga nidra is one aspect or form of pratyahara. When one practises yoga nidra he is not asleep. His consciousness is functioning in a certain state of awareness.
About 35 years ago when I was living with my guru in Rishikesh, I had a very important experience which triggered off the evolution of yoga nidra. I had been appointed to watch over an ashram school where small children were learning to chant the Vedas. It was my duty to watch the ashram by night and at four in the morning I used to sleep. Then after a few months my duties were changed. About a year later there was a function in our own ashram, and the children from that school came to chant the Vedas. When they were chanting, the words were totally familiar to me but I could not remember where it was that I had heard them. Casually I asked my guru and he told me that I had heard them chanting while I was sleeping in that school. This was a great revelation for me and a new discovery as well.
We know that knowledge is gained through the senses, but from this experience, I came to the conclusion that you can gain knowledge without any sensory medium as well. After that, further ideas came to my mind. I realised that sleep was not a state of total unconsciousness. When one is completely asleep, there remains a personality, a form of awareness, something very important and alert in man, that is awake and fully alive to the outer situations. I found that one who has trained his mind is able to utilise this state.
Thereafter, I did many experiments to validate these ideas. I tried yoga nidra on animals as well, and I even succeeded in training an Alsatian dog. Later on I experimented with yoga nidra on some of my own disciples. I worked with children, giving them knowledge, experience and instruction while they were sleeping soundly.
When I was studying tantric scriptures I came across many important but little known practices. Ultimately, I evolved the system called yoga nidra. In the beginning I used to call this sleepless sleep. Then I changed it and began to call it psychic sleep. But now I have become more and more aware of the vast potentialities of yoga nidra and I think that yoga nidra is nothing but yoga nidra! If you ask me to translate yoga nidra into French I will say yoga nidra! It is a very international practice.
Just recently I saw a research report from the Menninger Foundation in the United States. Under the direction of Dr Green, the researchers there wired up Swami Rama with an electro-encephalograph to record brainwave activity as he progressively relaxed the physical, mental and emotional structure through the process of yoga nidra. Of course, what they found was a revelation to the scientific community. He entered the state of deep sleep, as verified by the emergence of the delta wave patterns from his brain. However, he remained perfectly aware. He later recalled all the incidents in the laboratory, and every question one of the scientists had asked him during that deep sleep period. This is the state of yoga nidra that develops after mental training. Its rediscovery has profound implications for medical and social sciences alike.
When you practise yoga nidra you must remember that you are trying to evolve a most dynamic state of consciousness. This deeper state of your mind is dissipated during the waking and dreaming states. You have that dynamism even now but the tendencies of the mind are dissipated. There are a lot of distractions through the sensory channels, and we are unable to attain a profound state of consciousness.
This profound state of consciousness is such that even the sense of self-awareness is completely consumed. When you are concentrating you know you are concentrating, but when you are in yoga nidra there comes a moment when you do not know that you are in yoga nidra. When the mind dissociates itself from the sensory channels it becomes very powerful, but then it needs training. The involuntary systems of the brain have to be properly trained. Otherwise there is practically no difference between ordinary sleep and yoga nidra.
Most people still feel that yoga nidra is only a practice of relaxation, and yet, excepting the scientists, they don't even understand what relaxation means.
You are tired, so you go to bed and think you are relaxing. But unless you are free from muscular, mental and emotional tensions, you are never relaxed. These threefold tensions have to be eliminated; then the actual state of relaxation dawns. The practice of yoga nidra will eliminate these threefold tensions.
Many of you have heard the Sanskrit mantra 'Om shanti, shanti, shanti'. This chanting of shanti three times symbolises threefold relaxation. When you become free from muscular, mental and emotional tensions, then the mental state that dawns is known as 'shanti'. Usually shanti is mistranslated as 'peace', but shanti is actually a state of total passivity of distractions, dissipations and disturbances.
In the last 25 or 30 years that I have been working on yoga nidra with different people, I have come to the conclusion that the human mind should be made receptive first. Receptivity of the mind can be awakened only when the dissipations are annihilated. When you practise yoga nidra you are able to awaken this receptivity by awakening the emotional structure of the mind.
If I tell you that this is right and that is wrong, you will agree with me, but that is intellectual agreement. In spite of the fact that you agree with me, you may not be able to implement this in your daily life.
Once I was in an Indian village. I met a man who was a thief and robber, a hardened criminal. We were talking and talking and finally he was convinced that he was not doing the right thing. He even came to the point of feeling that he was a sinner and I believed that I had performed a miracle and had been successful in converting him! When I returned to that village after five years he was found to be the same man, for I had convinced only his intellect, not his self!
I then lived in that village for a period of six months, because at that time I stayed at every place for long periods. I used to teach yoga nidra in a school to the children and teachers. Fortunately, or unfortunately, he also joined the yoga nidra. He did not know that he was in a lion's den. I don't know how many sessions of yoga nidra he attended, but he left his profession shortly after.
Intellectual conviction is one aspect of human life and we are all intellectually convinced about good and bad. But we have to also be receptive emotionally to everything that we need to assimilate, and this is possible only when the dissipations and distractions of the mind are withdrawn. When the mind is flowing on one smooth level, the fluctuations and the waves in the mind are calmed. Then whatever is impressed upon the mind, that becomes the corrective, that becomes the destiny, that becomes the directive.
I tried yoga nidra first on those children who wet the bed at night. That was a very simple experiment. There was a child of six years who wet the bed at night. Every morning his mother said, 'Why did you do all this?' The child was sorry, and at night the mother said, 'Don't wet the bed tonight.' The mother kept telling the child, and the child went on wetting.
I brought that child to my bed. When I saw his head was on the pillow, I told him a short story. Not a long one, but a short one, and I instructed him, 'Each time I stop, you say "hmm".' After a minute or two he stopped responding. I called him by name and asked 'Do you understand my story?' That released a response, 'Hmm'. I then asked him 'Are you listening now?' And there was no response. I immediately woke him and said, 'If you feel like urinating, please wake me up.' That was enough to cure the habit. I carried out the same experiment on many such children and they all stopped wetting the bed.
The mother admonished him every day. The child heard it, felt it, was afraid of it, but still he wet the bed. When he was in a state of sleep at the first stage of consciousness, he did not know what I was telling him. There was no reason even why he felt it, because he did not understand. Maybe he didn't even hear me properly because his brain had retreated into silence. What affected him at that time and what relationship is there between that state of the brain and the external situations? If that child was given another form of instruction, if he was taught Italian, French or German, or if he was taught some kind of criminal things, he would have accepted them also.
Today many researchers are utilising the discovery of this deeper inner personality to evolve new systems of education which bypass the normal intellectual processes of the conscious mind. These are based on the experiences I had in Rishikesh and point to a complete revolution in the educational processes. In Bulgaria, Dr Lozanov, head of the Institute of Suggestology and Parapsychology in Sofia, has developed Suggestology, based on the technique of yoga nidra. It involves deep relaxation of muscular tension within the body and the worries and anxieties of the brain and mind. A state of deep relaxation and receptivity follows, which produces alpha waves. Dr Lozanov has used this state to teach people a foreign language in a fraction of the time that it normally takes. He has also used this state to treat neuroses and allergies, to induce anaesthesia, reduce blood loss, enhance wound healing and decrease infections after surgery, as well as to enhance psychic abilities.
So many wonderful things are evolving from the gradual merging of yoga and science. There is, however, one point which has to be made very clear. Modern education methods are based on yoga nidra but they are not yoga nidra. While the principle of relaxation of physical, emotional and mental tensions and of opening up the subconscious recesses of our psycho-physiological personality are the same, many modern techniques are a form of hypnosis. They cultivate a passive, suggestive state - a state in which the subject does not consciously participate. The guide can then bypass the intellectual processes to plant remedial suggestions, attitudes, concepts, philosophies, personal ideas or lists of information for storage. The power of the guide's personality is used to implant whatever is desired in the mind. That is a type of hypnosis and it is very effective for what it is designed to do.
However, is everyone capable of taking on the great responsibility of trying to develop another individual's innate capacities and potential? Do we have the ability to take on the changing of another person's mind and inner personality? To do this properly one must be free of tensions, neuroses, complexes and all personal problems. He must have a deep understanding of the relationship between body and mind. The long term effects of such training have not been fully explored scientifically. After all, many great discoveries, such as the splitting of the atom, have been misused.
Yoga nidra is altogether different from hypnosis. In yoga nidra we use the concept of autosuggestion for only a few seconds, and we call it sankalpa, the resolve. Yoga nidra is a dynamic method by which the individual consciously cultivates his inner faculties. Instead of planting knowledge inside, in yoga nidra we allow the intuitive inner knowledge to blossom forth. Memory, sensitivity, relaxation, intelligence, ability to control the senses, and so on, are just a few of the dormant faculties within, waiting to be awakened and tapped. These are just side products of the main process which leads to the dawning of greater awareness, to the evolution of consciousness. This is achieved by consciously participating, by learning how to dive into the mind and the brain and activate the various switches and internal mechanisms that lead to new modes of perception, creativity and intuition, to the source of all outer knowledge. All this comes from one simple technique that can be used by anyone.
So in yoga nidra we have realised that there is a state of mind which is very sensitive, very potential and absolutely receptive. In children that state of mind occurs readily, but for a very short period. In adults like us, whose brains are already seasoned, it takes time for this state to occur.
In recent years yoga nidra has been applied in cases of hypertension and blood pressure and also in cases of insomnia. I have been working on this with some medical men in India for the last five years. A few years back a research project in Patna was begun by Dr Shreenivas, director of the Yoga Research Institute and aided by the central government of India. It investigated the effect of yoga on coronary diseases. There were eminent cardiologists working on this project and my institution and myself were co-ordinators.
Dr Shreenivas took 150 people for his experiment. Their blood pressure was measured and then they were asked to take a tranquilliser. After 30 minutes of resting in this state their blood pressure was measured but no appreciable changes were found. Two days later they came back and underwent our system of yoga nidra. There was a significant lowering of blood pressure in a high percentage of cases with none of the side-effects of potent drugs and medicines. Coronary research study is now complete and the report is being prepared.
In some cases of heart disease and high blood pressure we are obliged to give some medicinal doses, but in many cases patients can go without medicines. I am not against medicines, but I don't like people to depend solely on them because I don't think that medicines can give health. However, I know that when the situation is very acute it is necessary to take medicines as well, especially when the patients are suffering from coronary diseases such as angina, cardiac ischaemia and myocardial infarction. However, once they start to practise yoga nidra, they feel more relaxed and can gradually leave all medication.
In addition, I am involved with another Indian medical research project. We developed a particular system using yoga nidra for those people who suffer from hypertension. We have conducted quite a few courses of instruction for them. In each seminar there were roughly 25 patients, both men and women, ranging from 35 to 80 years. Their average achievement was 53%. In almost all cases we succeeded very well. Those patients in whom hypertension did not come down in response to yoga nidra, were found to be purely cases of arteriosclerosis, where healing requires additional techniques and more time. Others did not complete their training or carry it on for a sufficient length of time. However, all found that yoga nidra made them feel better. Thus it is of profound value in the treatment of all kinds of diseases, especially where active physical exercise is prohibited.
Director of the department of cardiology at the K.E.M. Hospital in Bombay, Dr K. K. Datey, has had very similar results to ours using yoga nidra to combat high blood pressure. He calls the technique shavasana, but this is actually the name of the posture, not the relaxation technique itself. Dr Datey used yoga nidra for 47 hypertensive patients whose ages ranged from 22 to 64 years, and found that he could get a satisfactory and significant response in over half his patients. Again there was no response in patients with arteriosclerosis, however, the vast majority of his patients achieved symptomatic relief and a sense of 'well-being'.
The use of yoga nidra to overcome various disease states is becoming a new and exciting venture for scientists. Cancer therapists in Australia and in Texas have applied the techniques of yoga nidra, including deep relaxation and visualisation, in their work on cancer. They have reported some very good results in the medical journals up to the present and their work is continuing.
In the field of psychology, some workers are utilising yoga nidra to enhance the dormant skills and abilities of experimental subjects. They are even using yoga nidra to win medals in the Olympic Games. Those athletes are not hypnotising themselves but are developing their inner potentials.
We must try to understand yoga nidra in relation to the yogic state of mind. I don't say that it is a therapy, nor even that it is a system of treatment. It is essentially a system of training by which you are able to bring about the desired state of awareness.
Scientifically it has been found that when you practise yoga nidra the central gyrus of the brain is influenced. When you practise awareness of each and every part of the body it is not just a monotonous kind of concentration. Whenever you fix your awareness on one of the parts of the body it is an act of monitoring an influence upon the higher centres of the brain. Do you understand what I mean here by the word monitoring? Commanding the higher centres of the brain.
The outer surfaces of the centre of the brain are composed of various folds of white matter. These are called gyri. Along the central gyrus of the brain each and every part of the body has a counterstation, a place or point. The thumb, 2nd, 3rd, 4th, 5th fingers, wrist, elbow, shoulder, etc., all these areas are represented or projected on that gyrus.
Cross section of the brain revealing the motor cortex and indicating the areas of the body as mapped along the precentral gyrus. This is the motor homunculus - the symbolic man lying within the brain matter.
|1. Toes||9. Hand||17. Eyelid and eyeball|
|2. Ankle||10. Little finger||18. Face|
|3. Knee||11. Ring finger||19. Lips|
|4. Hip||12. Middle finger||20. Jaw|
|5. Trunk||13. Index finger||21. Tongue|
|6. Shoulder||14. Thumb||22. Swallowing|
|7. Elbow||15. Neck|
|8. Wrist||16. Brow|
In yoga nidra we relax the mind by relaxing the body. We say right hand thumb, 2nd finger, 3rd, 4th, 5th... in a monotone voice, thereby relaxing the parts of the body along with their related points in the brain. It has been claimed that we are creating a state of hypnosis by the monotone voice but yoga nidra is far from hypnosis. It is a practice of yoga and it is one of the states of pratyahara.
In the raja yoga of Patanjali, the fifth stage is pratyahara. The first stage is yama, then niyama, then asana, pranayama, pratyahara, dharana, dhyana; and samadhi - the ultimate. This pratyahara is a very special faculty that has to be cultivated. When you cultivate this faculty of pratyahara you can utilise it for self-therapy or you can develop it into concentration, meditation and samadhi.
There are certain forms of pratyahara which carry the mind very deep. In those practices of pratyahara the brain is completely disconnected from the sensory information. You receive sensory perception through the eyes, through the nose, the ears, the tongue, and the tactile receptors of the skin. Even if the eyes are closed or you are unable to hear, you can still receive information in the brain through the tactile medium. But as you go into the deeper practices of pratyahara the dissociation becomes complete. All the sensory channels are not capable of supplying you with the necessary amount of information. When this absence of information takes place then the mind has to be hanged to the practice of dharana, concentration.
When pratyahara becomes deep and powerful and total isolation of the brain takes place, the silent areas of the brain are affected and energy flows around them. During this moment of isolation of the brain the cerebral fluid which flows around the brain beneath the skull is charged with a special energy.
The late Dr Itzak Bentov developed a sound scientific model of this process. He recorded that standing resonant waves are set up in the circulatory system in deep meditation. In response to these waves, small rhythmic currents and wave forms are generated within the fluid surrounding the brain to gradually awaken the higher cerebral and psychic faculties and centres. Then you have certain psychic experiences.
In yoga nidra these deep psychic experiences must be avoided. When you begin to develop psychic awareness you are going beyond the range of yoga nidra. This is the fundamental difference between deep and light pratyahara. In the state of yoga nidra you are on the borderline. When you go into the deep state of pratyahara, it is no longer yoga nidra.
We must see that yoga nidra has no visions, no psychic explosions, no psychic developments, or experiences. The only thing that is acceptable in yoga nidra is that the voice which you hear becomes remote, as if someone is talking to you or whispering to you from a great distance. The flow of motion in the mind is continuous; the pattern of awareness remains constant, unbroken. You are not on the psychic plane, but you are on the borderline of the conscious plane. The quantum of consciousness is not the same as it is now; it is not the same as when you are thinking. This is a very beautiful state which scientists call the hypnogogic or hypnopompic state but which I call the threshold between this and that.
In the practices of pratyahara, voluntary efforts help the mind to withdraw from dissipation and distraction, but in yoga nidra we try to eliminate this possibility because the moment there is concentration, there is also an element of exertion. Any voluntary effort made to achieve concentration generates a little bit of tension in the brain. So in the practice of yoga nidra the flow of awareness is smooth and constant.
Everybody has his own limitations and I have my own. I have to look to the administration of so many ashrams spread all over the globe, then I have to look to disciples and everybody. Therefore I am unable to continue my experiments on yoga nidra, but I am firmly convinced that it can change a man completely.
You can teach yoga nidra to yourself. Anything in life can fail, but if you make a decision in yoga nidra at the right moment, it will never fail. Try yoga nidra on any form of disease, try yoga nidra in your family situations, and see what benefits it brings.
I call yoga nidra 'taming the wild monkey'. It is a technique of taming this wild monkey, the human mind. This anarchical mind, this disorderly and broken and schizophrenic mind can be brought into a beautiful pattern if yoga nidra is rightly practised.
Please tell us more about the actual practice of yoga nidra.
It is a practice which generally lasts for 20 to 40 minutes. There are separate techniques for people suffering from hypertension and for those who want to make some decision in their life. There are other techniques for those who want to go deep into the spiritual side of yoga.
Yoga nidra is actually a very simple practice, and you can learn it from a tape or a record. Before starting, choose a quiet room and close the windows and doors. Put off the television or radio, loosen your collar and tie, and switch on the tape recorder. Then lie down in shavasana and listen to whatever the voice is instructing. Go on following the instructions mentally. No concentration, no pranayama, only listening and following the instructions mentally. The most important instruction in yoga nidra is 'Don't sleep'. If you sleep you lose the awareness, which is the point of yoga nidra.
What is the correct state in which to practise yoga nidra?
First of all you must direct yourself by listening to a tape or any instructing medium. Don't aim at going deep. That is the greatest mistake we make, not only in yoga nidra but also in the system of meditation. Try to be very spontaneous, very relaxed and very much at peace with yourself. Even if the brain does not co-operate sometimes, this is not bad. Periodical distractions which come from time to time will help you in yoga nidra because they keep the awareness in a very alert condition and don't allow you to slip in and slumber.
Why isn't it recommended to give the instructions of yoga nidra to yourself?
How, when there is a lot of tension? You will strain yourself to remember 'right hand thumb, and what is next? Second finger, then?' and so on. In order to give the instructions to yourself, the entire practice must be very clear in your mind so that you don't have to stop anywhere and try to remember what comes next. Therefore, in the beginning it is much better to simply practise by following the instructions on a tape recording, or your teacher's voice.
Of course, after some time you will be able to practise the whole process unaided by any external agency. You will both initiate the instructions and respond effortlessly to them.
What is the best way to give yoga nidra to others?
When you teach yoga nidra, you should not stay on any one point for a long time. Move fast - right hand thumb, 2nd finger, 3rd, 4th, 5th, etc., keep on jumping. Don't allow any time for concentration or psychic images will come. Yoga nidra is not concentration. The images for visualisation, like guava tree, rose flower, boat on a river, sandy beach, and so on, should be precise and in rapid succession. When you give extended visualisations such as walking in the park, golden egg, a story, etc., the images should be adjusted in such a way that they serve as stepping stones to further concentration practices later on.
If you are teaching yoga nidra to children, don't tell them anything, just give them inner visualisation, distinct un-associated images in rapid succession, using numbers, colours, forms, flowers, trees, environmental scenes, or something imaginative. This is actually the ultimate point in yoga nidra and the purpose here is to check your perceptive capabilities.
If I say pink rose and you imagine how it looks, this means that your receptivity is keen. If I say pink rose and you try hard but you can't picture it, this means you have not yet come to the point of receptivity. If I say pink rose, and you see the rose as a slight inter-psychic vision, then you have gone too deep and passed beyond the state of receptivity. In visualisation, rapid sequence images most effectively retain the receptive state.
What is the difference between deep sleep and psychic sleep or yoga nidra?
Yoga nidra means sleep with a trace of awareness; nidra means unconscious sleep. Everyone undergoes the state of yoga nidra each night before they go to sleep. It is a state of mind in between wakefulness and dream. At this time your consciousness is operating on both of these levels, but has no association with either of them. Within three minutes of lying down children enter into this state of psychic sleep. Adults who have more problems and worries in their life may take longer. Unless you are familiar with the practice of yoga nidra, this state remains for about three minutes before you slip into deep sleep (nidra).
Psychic sleep takes place at the threshold of sense consciousness and sleep consciousness. The threshold state produces alpha or theta waves as a rule. In the practice we isolate the brain, we become introverted, but we maintain a degree of external awareness by listening to and mentally following a series of instructions. Otherwise what happens is that after the brain is isolated for sometime, it becomes inactive and delta waves appear as deep sleep supervenes. Then the yoga nidra state is lost as the awareness slips down into unconsciousness.
How are you able to correct bad habits or attitudes in yoga nidra?
Yoga nidra is a method by which you can influence your mind. If you are addicted to a certain bad habit which you cannot eliminate, at a particular stage in the practice through the power of suggestion, you can make the mind follow your orders. Within a period of 10 to 20 days you will be free of that bad habit.
It can also be used to influence small children up to the age of 8 or 10 years. In the state of yoga nidra you can suggest certain new behavioural patterns for them to follow.
The threshold state just before the appearance of delta waves or deep sleep is very receptive. If you want to stop a child from bed wetting, for example, the impression of urinating in the toilet rather than in the bed has to be firmly fixed in this state. The child should hear but at the same time he should not be consciously aware of what you are telling him. The brain registers the impression at a subconscious level and from there it works on the consciousness in a more powerful way.
Isn't this a type of brainwashing?
Brainwashing is a method which was designed for political blackmailing. If you call yoga nidra brainwashing then I think there is nothing in this world that isn't brainwashing. What are televisions, radios, advertisements, newspapers, magazines, and novels doing to our brains every minute of the day? It is really very good if the brain is washed with something clean.
In the receptive state created by yoga nidra we are able to correct the negative patterns already existing in the brain. Take a girl suffering from a fear psychosis. Doctors have tried all methods to treat her but failed. If you are able to resolve her fears by injecting one simple idea into her mind, is this brainwashing? Perhaps, but in a positive sense.
In yoga we are taught to follow the path of knowledge, where we experience the pain, the sorrow, the agony, and then transcend it. This is the best way, but is everybody capable of understanding and transcending their pain? For those who are not, this way of brainwashing is useful. After all, everybody is brainwashing himself all the time anyway. How to stop it? You don't have the awareness to stop it, even if you wanted to. You can only do it in samadhi, perhaps, but not before.
What is the power of sankalpa and how does it work?
A sankalpa is made twice during the practice of yoga nidra, in the beginning and again at the end. Sankalpa is a thought in the mind. Everyone has many desires and many thoughts. When you have a desire, you are aware of it and again it goes back into your mind. Most desires get lost, exhausted, or destroyed; just as when you scatter seeds in different places, some may grow but most will not.
Sankalpa is a seed, which you create and then sow in the bed of your mind. When the mind is clear, then the sankalpa grows very well. If you first prepare the bed with fertiliser and manure, remove the weeds and grass, and then plant the seed, it will grow better. In the same way, you have the mind and you have an idea. If you prepare your mind and then sow the seed, the idea, properly, then it will grow in your life and become willpower.
Everyone knows that we are an outcome of ideas. The whole creation or existence is the result of an idea. If there is no idea, there is no creation. Whether you are a carpenter, businessman, teacher, scientist, engineer, or a yogi, that is the outcome of an idea. When we realise the limitations of our life, we want to do something. At that time, we create an idea in the mind and we develop that idea through sankalpa made during the practice of yoga nidra. As the idea develops, it influences the mind very powerfully, and it becomes a reality in the course of time.
So before you start the practice of yoga nidra, you first create an idea. Although your mind is not yet tranquil and stable, by the time you come to the termination of the practice, it will be. At that time you again become aware of the same idea. This is how the idea becomes what we call a reality in one's life.
If you want to transform your life pattern, that can be done by the sankalpa made in yoga nidra. If there is a negative tendency or habit in your life and you want to correct it, that can be done by a positive sankalpa. Sankalpa means willpower.
How do you formulate the sankalpa?
Sankalpa is a very powerful instrument in the hands of man. Sankalpa should only be made when one understands its real purpose and meaning. In the beginning most people do not know what sankalpa is or which sankalpa they should make. Therefore they should wait until their understanding develops.
Sankalpa can create a direction for your whole life if you use it wisely. But if you use it for the eradication of smoking or drinking, then you are misusing it. This is something like shooting a rifle at a fly. The purpose of sankalpa is to influence and transform the whole life pattern, not only the body but also the mind, the emotions, and the spiritual forces. Then if you are a heavy smoker or drinker, you will automatically give it up. When sankalpa becomes the directing force in life, then life becomes successful.
Experiments have been made using yoga nidra for out of the body experiences. Is this also an aim of yoga nidra?
In yoga nidra, if you can remain awake, and if you are able to cut off your external awareness but intensify your internal awareness, and at the same time you can keep your mind moving, then you can try to go outside. Why not? But be sure that you can bring yourself back inside again.
Such experiences are possible, but they are not the aim. Yoga nidra is a practice by which you can awaken your consciousness and separate it from external awareness and from sleep. Then the consciousness becomes powerful and you can apply it in any way you like. You can develop the memory, increase knowledge, do astral traveling, transform your nature, eliminate many vicious habits of thinking and living. The aim of yoga nidra depends mostly on the practitioner.