Why do shift workers do not sleep well during the day?

Our biological clock is using the natural light as a signal to synchronize activity and rest periods. After a night shift, when the worker gets exposed to natural light on the way home, the clock receives a signal that it is daytime and therefore not the time to sleep.Chron-optic© glasses can be used to trick the body clock to "believe" that is it night time, and therefore time to sleep! Here is how it works. Our biological clock "sees" only certain colors present in sunlight, namely blue and some green.Chron-optic© glasses were developped by scientists who demonstrated that these glasses can render "almost blind" the body clock. These scientists also demonstrated that night shift workers who wore Chron-optic© glasses after a night shift could improve their sleep by an average of 30 min per day!