Researchers at the Cincinnati Children’s Hospital Medical Center have found no evidence that Night Shift on a smartphone improves sleep in any way.
It is believed that the blue color of the screen impairs the production of melatonin and disrupts the cycles of sleep and wakefulness. In 2016, Apple added Night Shift to its iOS devices, which adjusts the screen to warmer colors in the evening. Then there were phones with the Android operating system, equipped with a similar function. It is believed that such a night mode improves the process of falling asleep and the quality of sleep.
The study involved 167 people aged 16–24 who use smartphones daily. They had to spend at least 8 hours a day in bed and wear an accelerometer on their wrist to measure activity. Also, using a special application, scientists tracked how they use the phone.
The scientists divided the subjects into three groups: those who used the phone at night with Night Shift turned on; those who did not use this feature; those who did not use the smartphone at all before going to bed. They did not find any difference between the groups.
Then the subjects were divided into two groups: one slept about 7 hours per night, and the other — less than 6 hours. In this case, there was a slight difference. Those who slept for 7 hours (which is closer to the recommended 8–9 hours) slept better if they did not pick up the phone at all, and worse if they used it before bed, regardless of the inclusion of Night Shift. The group that slept less than 6 hours showed no difference in the quality and quantity of sleep, with or without a phone, with or without Night Shift.
Thus, the Night Shift mode does nothing to help a person fall asleep or sleep better.