Everyone knows that good sleep is important, but not everyone knows how important it is (sleep)in the dark. A new report said sleeping with the light on (possible)increases the risk of getting some diseases. Even the light a television or clock could be harmful to our health. The report also said that of different kinds of lights, the (bad)to sleep with is a main light. Sleeping in the dark is more difficult for the people live in cities, where there is a lot of outdoor light at night.
Dr Phyllis Zee is scientist in sleep medicine. She said it is healthier for us to turn off all lights when we sleep. Her team had a study of the blood sugar levels(血糖)of 20 people after several (night)of sleep. The people who slept with a light on had higher blood sugar levels the next morning,(compare)to those who slept in total darkness. Dr Zee said this would raise blood sugar levels the light stimulates(促进)brain activity. She said there is something we can do (reduce)the risk of illness: turn off the lights, never sleep with white or blue light.