Have suggested vitamin D to her, for obvious reasons, and the melatonin idea.
Don't think the permenant night shift issue has been raised enough.
Daughter comes home from work at 6am, sees that as her tea time, (during the week)
Goes on commy for a while, has something to eat, then depending on how she feels, goes to sleep for the day. Still has to fit in nomal stuff during daylight hours, like going to the bank and such, which interrupts her sleep pattern.