Hello and thanks for researching this very important question!
I am so sorry that you are having this difficult and distressing experience...please continue to maintain a high degree of caution when around this dear pet while he sleeps.
Although unaddressed dominance can produce a dog that does not like to be disturbed during sleep, there is now a lot more that we know about the sleeping brain than ever before.
Sudden onset of aggressive behaviors can be a result of physical illness, injury, or chemical imbalance in the brain. Seizures occuring in the hypothalamus will certainly produce aggressive behaviors. Dips in serotonin levels during sleep have been associated with sleep apnea (breath-holding), and has been associated with aggression in dogs generally.I've attached a few links that you can use to examine the medical basis for this type of behavioral change:
http://www.petplace.com/dogs/medical-causes-of-aggression-in-dogs/page1.aspx http://www.canlyme.com/dogagg.html You should seek the help of a Veterinary Neurologist who can help diagnose this behavior properly, and provide treatment, if possible. This link can help you locate a specialist if your regular vet does not have a referral name for you:
If you need additional support at this time, please click "Reply", otherwise I thank you in advance for your "Accept" and will keep a Good Thought that you can get some help!