The bus journey wasn't that bad as it happened. The environmental conditions inside were okay; the heat disappeared pretty quickly; the temperature was nice till sundown, then I put more and more clothes on until I ran out. My feet got cold, but the rest of me was okay. The motion was a bit wierd and rolling, but in general I like travelling overnight and with horizontal. If there was some kind of night bus in the UK, I think that I'd take it pretty often; obviously I'd prefer something that wasn't packed to the rafters and has some basic safety standards.
Oh, and a toilet.