Agent Smith can keep people asleep until they die, and reinforce their sleep

“I’ll be honest, George. I’d kind of hoped you’d all just pleasantly live in your little dreamworld until you starved to death, but …” She stopped and looked at him. “It was Sorensen’s kid, wasn’t it? I knew she was going to be a problem.”
“She remembered you,” said St. George. “She knew you were up to something.”
Christian Smith smiled and shook her head. “It’s the little details that always get you in the end. She almost got you out of it yesterday. You probably would’ve woken up if I hadn’t been there to give you a few fresh commands.” She straightened up and brushed her suit down. “Anyway, we should get going. Could you follow me, George?”

Excerpt From Ex-Purgatory, pg 581
Peter Clines
https://books.apple.com/us/book/ex-purgatory/id676938479