Why is it so unbelieveable that the McCanns drugged their kids?

They want us to believe they got back to the apartment, bathed 3 children, got themselves ready to go out, and then miraculously got all 3 kids asleep all within a couple of hours and then went out by 7.30pm. yeah right. It used to take me longer with just 1 child. Bearing in mind this was not the first time they had left their kids. Sedatives from the parents point of view would be ideal, maybe thats why they were happy to go off boozing as they were sure they would not wake up.