Body Loves a Schedule

Switching to different schedules is actually less healthy than sticking to one schedule for a long time. The reason is that your circadian (day/night) cycle is synchronized with a hormone (melatonin) that is secreted by the pineal gland. This is stimulated by the light/dark cycle, and when disrupted, can throw your sense of being 100% awake and sharp for work. If you keep changing, you will be more likely to perform at a lower level of efficiency, and perhaps make more mistakes.

Timothy Sly, Public health epidemiologist, Toronto