The human body should keep the environment quiet and light dark when sleeping, which can improve the quality of sleep. Sleeping with the lights on is easy to disrupt the body’s biological clock, causing certain harm to the body: 1, affect melatonin secretion: in a dark environment, the body secretes a lot of melatonin, which has the effect of promoting sleep and enhancing immune function. As long as the eyes feel the light source, melatonin secretion will be inhibited, long-term immunity will also be reduced as a result; 2, disrupt the biological clock: the biological rhythm of sleep is established with the appearance as well as disappearance of sunlight, if long-term sleep with the lights on, the light as well as the brightness will lead to disruption of the biological clock, so that the endocrine organism is affected; 3, affect eye health: the light during sleep will lead to the eyes have been able to feel the Light source, stimulating the movement of the eye at night, resulting in abnormal ciliary muscle function; 4, affect the absorption of calcium: infants who are often under the light at night, the body’s absorption of calcium will drop by about 25%, which will have a serious impact on the late growth and development of infants.