snapping when disturbed while sleeping

Question
Hi,
I have a retired racing greyhound who is 5.  We have had her for about 5 months.  She is a great dog, but when she gets bumped or jostled while sleeping on her bed, she snaps.  She has never actually bitten, but I have two kids (8 &10) in the house and obviously this is a behavior I want to discourage.  Even when I am sitting on the floor with her, petting her while she naps/lays there....after she gets tired of it she has snapped once or twice.  I verbally scold her when she does this, but am looking for other suggestions.  Do you have any ideas?

Answer
Use a water bottle and spray her when she does that and say 'no'

You might also want to look into taking her to obedience classes-as this can become a very serious issue and a trainer can work on it as they see it-call around different trainers and tell them the snapping issue and pick the one you like the best