Not a bad or lazy parent at all - if anything the opposite is true. I would be wrong to put the child in danger by risking you falling asleep from the meds or making mistakes due to your state of mind to keep him in the home when there wasn't any other adult able to be there too.

I get where you are coming from though as in I'm sure all kinds of weird scenerios went through your mind about why some of the other children were in care there that day but if the teacher suggested it then she too knows what the role of the day nursery is and for your son it was the best place to be.