0Shavasana is a asana which is like assuming dead body It works relaxation of mind and body and can be done after completion of asanas and pranayama even it can be done at any time.
Technique of Shavasana -After completion of asanas one can lie down on back,then keep distance between two legs and hands crossed to the shoulders.Then start observing each and every part of body which start from right leg to right shoulder and from left leg to left shoulder.Then back parts I.e. vertebra and it's ligament then come at stomach and chest and all parts.Face and throat.Imagine all the Parts of body as well joints ,muscles are relaxed.
Now focus an attention at tip of nostrils and observe the breathing movements.While observing breathing pattern your mind may go other places.Try to focus attention at nostril and leave the thoughts,worries outside of mind.By doing this process mind become calm and relax.One can take deep breath and excel out slowly.
Finally,one can check up whether relaxation is ok by keeping mind towards pain if any in any part of body.If the relaxtion done properly the pain may be disappear.Therefore it called king of all asanas.If one can done five minutes shavana it is equal to five hours sleep.
