It’s not unusual for many people to leave a light or even the television turned on while they sleep. New research has uncovered information that should discourage that practice.
Researchers from the Samsung Medical Center of Sungkyunkwan University School of Medicine in Seoul, South Korea, had 10 healthy people sleep for two nights while machines assessed changes in their heart rate, breathing and brain and muscle activity. The first night, there was no artificial light in the room, but during the second night a fluorescent lamp was placed a few feet from the sleeping subjects.
The total amount of time people spent in bed and the time they spent sleeping were similar whether the light was on or off. But, with the light on, sleepers spent more time in stage 1 sleep – the shallowest kind – and less time in stage 3 and 4 sleep. The difference was equivalent to giving each of the subjects sleep apnea.
Nine out of the 10 sleepers reported feeling like they got poorer quality sleep when the light was on. Also, the researchers recorded more “micro-arousals” with the light on. These micro-arousals were periods when the brain appears to be nearly awake for more than three seconds.