A lot of delicate flowers (and wannabe tough guys) on here. Tapping, nudging etc someone to attract their attention, whether asleep or not, is perfectly permissible and that's all that happened.
Ok thanks folks.
I really didn't expect such a wide and diverse set of views.
In future if this happens again, I shall ensure no physical contact is made but will still ensure that the culprit is made aware that he is disturbing half of the cabin-yes it really was that bad. It may be public transport but people are entitled not to be affected unduly by those around them. If it had been kids running around causing a disturbance then I think we would all expect the parents to control them. I would expect that if it's pointed that you are disturbing people be it by snoring, being unduly loud talking or any other way then people have the right not to be affected
It has also amazed me that so many answers refer to any sort of physical contact being considered to be paramount to an assault-clearly the words "common sense" no longer exist to some people.
End of debate for me.