You will notice that during every class we do headstand or the preparation for headstand if you are not ready for the full pose yet. Why is that?
Mr. Iyengar (and in fact ‘the ancient books’) call sirsana the ‘King’ of asanas. Sirsa means the head. Asana is the pose. Salamba refers to the fact that this is the supported version of the pose, i.e. we are not free balancing on our heads but use the support of the arms. Salamba sirsasana is a balancing pose as you will all have experienced only too well. However, its benefits go way beyond giving us balance and poise. By regular practising this pose the entire body is reconditioned and nourished. This happens by stimulating the endocrine system – especially the pituitary and pineal glands in the head. The pituitary gland controls the function of several other endocrine glands and is thus sometimes called the master gland. It influences growth, blood pressure, some function of sex organs, the thyroid gland and metabolism. The main function of the pineal gland is to control the circadian rhythm by releasing melatonin.
Being inverse forces the blood to the head which promotes mental clarity. Iyengar says: “The asana is a tonic for people whose brains tire quickly.” (B.K.S. Iyengar: Light on Yoga, page151). The lungs benefit, too. They become more resistant against changes in temperature which helps to prevent colds, coughs and ailments of the chest such as bronchitis and asthma. Headstand keeps the body warm.
When we stand on our feet, no effort is required as it is a natural pose. When inverted in headstand however, we need to concentrate on executing the pose correctly. Faulty execution of headstand can lead to pain in the neck, head and back. It is thus not only important to balance but to constantly adjust minutely during sirsasana.
You should not practice salamba sirsasana if you suffer from high blood pressure, when you are menstruating, when you have existing head and neck injuries. Do not attempt this pose alone if you have never done it under supervision of an experienced yoga instructor.
(Source: B.K.S. Iyengar: Light on Yoga, The Aquarian Press, 1991, London)