The situation and the question that follows it are very simple. When I go to sleep with an intention to meditate before it, it is not rare that I feel sudden coolness touch the back of my neck, and, on other occasions, I feel as if mild burning was taking place on my back, just where my wings would be if I were an angel ( I don't know how to describe this place more precisely in English) - as if some coals were put there.
So, the question is - does anybody have an idea what could cause these sensations?

P.S. - I have no health problems.