Phone in bed: what screen time does to your sleep
Not every minute on a screen in the evening is equal. In a video-measured study of 79 adolescents across 323 nights, use in bed, especially interactive use, was associated with less sleep. A much larger Norwegian survey points in the same direction. Here is what the studies show, and what they do not prove.
The strongest signal is in bed
Researchers in New Zealand used wearable cameras to record screen use and accelerometers to measure sleep in 79 adolescents aged 11 to 14.9. Across 323 nights, total screen use in the two hours before bed was not associated with most sleep measures. The sharper signal appeared after the young person got into bed.
Not all use is equal
Every additional ten minutes of total in-bed screen use before trying to sleep was associated with three minutes less total sleep. For interactive in-bed use, the association was nine minutes less sleep for every additional ten minutes. Gaming showed an even larger association. These figures describe a small observational study; they do not prove that the screen use caused every lost minute.
The problem is rarely the screen in the evening. It is the screen in bed.
The large survey: nearly 39,000 students
A 2022 Norwegian student survey analyzed regression data from nearly 39,000 screen users aged 18 to 28. Each additional hour of in-bed screen time was associated with 59 percent higher odds of reporting insomnia symptoms and 24 minutes less sleep. Social media was not uniquely worse than other screen activities. The study was cross-sectional and self-reported, so it cannot establish direction or causation.
What concretely helps
The phone has a fixed place outside the bedroom at night. A clear cut in the evening that is not renegotiated daily. The first reach in the morning does not go to a display.
Boundaries like these are easier to keep with a fixed routine than with a nightly negotiation. The ctrl sleep mode is designed around that routine. The cited studies did not test BACK TO CTRL and do not establish a product effect.