Psychology says people who sleep with interesting and beautiful lights switched on at night aren't necessarily afraid of the dark. For some people, keeping a lamp, glowing object or ambient light on is linked to comfort and a sense of control. The habit can also help create a familiar sleep environment. A person may find complete darkness uncomfortable because it leaves the mind with fewer things to focus on. A soft light can provide a visual point of attention while the person prepares to sleep. This does not mean that every person who sleeps with a light on has anxiety or emotional problems. Personal preference, routine and the design of the room can also influence the habit.
