Actually it was unusual. He said "Howard, why am i so tired/or sleepy?". If a person says "i'm so sleepy" it's not unusual, but "Howard, why am i so sleepy" doesn't sound usual to me.
More likely, he was reeling and starting to struggle with life. Whatever killed each of them was a massive dose to "END IT"...what I call the killer dose and the imminent cause of death. Short answer...Danny was given drugs earlier to make him unable to resist the later Killer Dose. Same as Anna.
So then he hit Daniel twice. Maybe once before he left for "food" and then when he got back, Daniel was out cold and he hit him with the killer dose. Is that it? or close?
Dying by laying down and never waking up IN TWO CASES so intimately connected is virtually impossible because they occured in two different places. (Catch what I mean here? They didn't share the same potion on the same day in the same place.)
"So then he hit Daniel twice. Maybe once before he left for "food" and then when he got back, Daniel was out cold and he hit him with the killer dose. Is that it? or close?"
Depends on when he got 'food', but I keep remembering Daniel was functioning well enough to be observed assisting ANS at 6:20AM.
I think you're right about both ANS and DS being 'prepped' for the biggie, but when is the question.