Avoid glowing screens one hour before bed; if you must, read paper books or e-ink devices instead
Original: eternity4719 · source details
Original author: eternity4719 · Chinese source: · English adaptation: parveen0029. Translation and grade notes ↗
Bibliographic titles are retained in their original language.
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Cost and benefit at a glance
- Check the cost Cost ↓
- No cost involved. Giving up phone use one hour before bed requires willpower, especially when fighting long-standing habits.
- Then the source benefit Benefit ↓
- 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 …
In plain terms
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.
This guide's cartoon · show illustration
Enlarge illustrationOriginal illustration with Chinese lettering; the English dialogue is below. Humour is a reading aid, not evidence.
English dialogue
- Just five minutes of rest.
- One more notification!
Cost: what it takes
No cost involved. Giving up phone use one hour before bed requires willpower, especially when fighting long-standing habits.
Benefit: what the source reports
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.
Conditions, limits and disagreements
The 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.
Original references
Original bibliographic titles and links are preserved; some titles are in Chinese.
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
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