Before I trained to do my 200 hour Yoga Teacher Training course I had always rolled onto my right side to come out of Savasana, this had been the side all my Yoga teachers had directed me to roll to and I had never had a reason to question this. Then on my Yoga Teacher Training course we discussed this in some more detail and I realised that it was actually a rather important thing and that my students needed to know why I was asking them to do things …
Reasons for rolling onto your right hand side:
When you roll to your right side, your heart is above your organs, which means there is less pressure on your heart. Much of any asana practice is about opening your heart and the action of rolling to your right continues this opening and freeing from pressure.
There is a purpose in physical space for rolling to the right side which leads into the psychological aspects. Psychologically, rolling to your right side after savasana represents a heating, Yang energy. The right side of your body is related to the solar, masculine flows of energy of the major prana nadi, which flows along the right side of your spine. Your right side correlates with action and awakening setting undertones for ancient customs.
Traditionally, in India, it is encouraged to enter a room with your right foot. Also, in many parts of the world especially the east, we extend our right hand to greet one another.
Rolling to the right or east direction is symbolic of beginning and extending our grace into the world ahead.
All of that being said we always advice pregnant ladies to roll over onto their left hand side, there are also good reasons for this:
According to WebMD, rolling to your left side improves circulation, giving nutrient-packed blood an easier route from your heart to the placenta to nourish your baby. Lying on your left side also relieves the pressure of your uterus from lying on top of your liver, which is essential in the processing of nutrients and detoxification of non-nutrients. In can be denoted that the slight pressure on your heart from lying on your left side is optimum for blood flow.
Energetically speaking, the left side of your body is related to the lunar, feminine flows and is representative of a cooling, calming, Yin energy which is manifested by the prana, chandra nadi. The chandra nadi runs along the left side of your spine. which has deep associations with relaxation and restfulness.
This also applies to people who have low blood pressure for that very reason that there is more pressure on the heart increasing blood flow.