Skip glowing screens for one hour before bed; if you read, use a paper book or an e-ink screen with the front light off
In the experiment, reading for about 4 hours before bed on an iPad at maximum brightness delays sleep onset by roughly 10 minutes compared to reading paper books. It also lowers melatonin production by 55%. The next day, the body’s internal clock shifts more than 1.5 hours later, making mornings harder and requiring extra time to feel fully awake.
No cost involved. Giving up phone use one hour before bed…
In the lab the same people did both conditions in turn (crossover). One was reading an e-book on an iPad befor…
No cost involved. Giving up phone use one hour before bed requires willpower, especially when fighting long-standing habits.
In the lab the same people did both conditions in turn (crossover). One was reading an e-book on an iPad before bed, brightness at maximum, about 4 hours, for 5 nights in a row. The other was reading a paper book in the same dim room. Reading the glowing e-book delayed sleep onset by about 10 minutes versus paper (25.7 minutes versus 15.8 minutes). Evening melatonin was suppressed by 55%. The next day’s body clock (circadian rhythm) delayed by more than 1.5 hours; melatonin onset was 22:31 versus 21:01. The next morning they were sleepier and took longer to become fully awake.
Chang, Aeschbach, Duffy & Czeisler (2015). Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. PNAS. https://doi.org/10.1073/pnas.1418490112
Open source linkThe sample is small; conditions were tightly controlled in a lab. At everyday phone brightness and use time, the effect may be smaller. How much night mode helps was not measured. E-ink was not measured either. An e-ink screen with the front light off, like paper, is read by reflected room light, so it is grouped with paper; that is an inference from this study. An e-ink screen with the front light on is also emitting light; there is no data.