I have seen articles about increased health hazards from working nights and then not sleeping in the dark. I think it was claimed that a group of nurses under these conditions had a greater incidence of breast cancer. I find this a bit difficult to accept, until further studies get similar results.
I worked nights for quite a few years and hated it. But I wore an eyeshade to make it easier to sleep. I wonder if that would have protected the nurses in the above mentioned study.