The answer to a question like this was posted on July 14, 2012 in this site and was supplimented by Admn Pro by providing very informative website:
However I would like to say that these are non-issues. While supplicating (dua) no specific posture is required. One can supplicate at any time, any where (except in bathroom) and in any position, the only pre-requist for supplication is sincerety and good intention. Supplications to harm one-self and others are not allowed.
For one's satisfaction the above mentioned website is worth consulting.
And Allaah knows the best.