Visible light plays a very important role in human well-being. All plants and animals on Earth have developed mechanisms to anticipate the time of day based on the cycle of light and darkness, and we are all synchronized to this cycle by means of light entering our eyes. The regularity of this cycle influences our functioning throughout the day.Changing the timing of especially the start and the end of the light exposure will influence our feeling of well-being: early bright light will make you energetic in the morning, whereas late bright light will make you energetic in the evening.