Do the Swiss get the day off if their biorhythms go off kilter?

We don't know about this, but they should! Tube drivers for instance don't get much daylight so this is bound to have an impact on your biorhythms. Night shift workers tend to be more accident prone, and the sleepier you are the more likely you are to be overconfident. There have been studies that show that for nurses in the US, there was a 20% greater incidence of breast cancer which may be due to the cortisol they're producing.