McMac
I've done this bus trip during the day (loved it) but there is one leaving Madrid 1am arriving Sevilla 7am.
OVERNIGHT BUS I booked my ticket at the bus station (that really big one that I can't remember the name of
). I had previously tried to book on-line but got nowhere. Maybe you could just turn up and get one.
Very comfy bus with slightly reclining chairs and a toilet. It stopped twice between Madrid and Sevilla, but not sure if it would do that in the night?
Good luck.
I went to a football match in Sevilla and loved it - I hate football normally
Jo