Seroquel and Haldol belong to the class of medications called antipsychotics. All these medications can cause stupor if they are used in high doses. It would be preferable to treat
his possible depression by higher doses of Zoloft (50 mg is a minimal starting dose) and if necessary potentiate the effect of Zoloft by administration of Abilify. Abilify is also an antipsychotics but it was recently approved for combination with antipsychotics and is probably the least likely to cause sedation.
"Hollering" at night may be caused by a lack of activities during the day that would keep him from napping. He would benefit from being on an Alzheimer unit that would have an appropriate activity program.