Research serotonin levels. Dogs prone to aggression are worse in the evening due to natural body rhythms. Also, have you had any medical work up done on him? Thyroid? I'm not one to jump on the neutering band wagon but in this case I would consider it. Removing the testosterone may help in your case.
And above all else...get a good trainer. When the dog is sleeping, put him in the crate. Since this is happening at night and early morning, he should be put in the crate every night.
And with a toddler in the house? I would be looking for a new home for this dog.