Biologists are collecting some extremely useful data about cyan, especially as it pertains to sleep. Cyan is a greenish blue colour that is commonly seen on computer screens and mobile devices of all sorts. Researchers at England’s University of Manchester say high levels of cyan can keep people awake, whereas low levels can help put them to sleep. The difference in the levels can be very subtle, often not visible to the human eye. “This outcome,” according to professor Rob Lucas, “is exciting because it tells us that regulating exposure to cyan light alone, without changing colour, can influence how sleepy we feel.” More and more studies are being conducted on screen time and the impact light has on our life/work patterns. As it turns out, cyan is proving to be a complex colour.