Avoid glowing screens one hour before bed; if you must, read paper books or e-ink devices instead
Reading from glowing screens before bed 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 controlled lab experiments, the same participants were tested under both conditions (cross-over design). Th…
No cost involved. Giving up phone use one hour before bed requires willpower, especially when fighting long-standing habits.
In controlled lab experiments, the same participants were tested under both conditions (cross-over design). Those reading from glowing e-readers fell asleep about 10 minutes later than those reading paper books (25.7 minutes versus 15.8 minutes). Their nighttime melatonin levels dropped by 55%, and their circadian rhythm shifted by over 1.5 hours — melatonin secretion started at 22:31 instead of 21:01. This resulted in greater morning sleepiness and a longer recovery time to full alertness.
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 study involved a small number of participants and was conducted under tightly controlled lab conditions. Real-world effects may be smaller given typical phone brightness and usage patterns. The study did not evaluate how much nighttime screen modes actually help.