I don't think it would be a good idea for any crew to be so tired they were asleep, even if it were just the ones sitting at the doors!
True! Which is why it is so difficult to understand why so
many BA cabin crew feel that shopping on a layover, particularly in North America, is so much more important than planning their rest properly during that layover. The resulting moans about tiredness et al on the return journey just don't cut the mustard, do they?