Dear Ananda members, please help me to know more details about following experience, Although I do not know if it is common.
During Meditation (simple breath observation), when I reach a stage where I am almost not breathing, the head is pushed backwards on its own and the mouth starts opening wide, I remain in that state till I allow that to happen. But during this time body is very light, almost nill breath and I experience peace in mind and body.
God be with you and everyone!
From your description, you are able to go deep into meditation and absorb yourself in peace. When you meditate, and able to go into breathless state, your energy is withdrawn into the deep spine, and you are not aware of your body. These symptoms of the head tilted back and the mouth open can happen. Keep your practice, making sure that you are sitting upright, your body is relaxed, and practice with deep devotion to God.