03-008 · EVIDENCE B · LOW-RISK READING
Avoid glowing screens one hour before bed; if you must, read paper books or e-ink devices instead
睡前一小时不看发光屏幕，要看就看纸书或墨水屏
No cost involved. Giving up phone use one hour before bed requires willpower, especially when fighting long-standing habits.
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.
B
Move “Avoid glowing screens one hour before bed; if you must, read paper books or e-ink devices instead” to Future Me's calendar
The excuse
If I do not open the notes, no new task has technically appeared.
What feels good now
Today I keep a few minutes, a bit of persistence and avoid interrupting my default routine.
What the source says
The source summarizes the return this way: “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.” Evidence grade B. The original states the population, caveats, and sources; this is not a personal forecast.
Open the original entry, check who the evidence applies to, then pick one small step that fits.
THE ENGLISH EDITION
Original recommendation and evidence
8. Avoid glowing screens one hour before bed; if you must, read paper books or e-ink devices instead
Cost: No cost involved. Giving up phone use one hour before bed requires willpower, especially when fighting long-standing habits.
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.
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 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.
Evidence grade: B
Sources: 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>
Notes: 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.
Read the complete Chinese source and notes
8. 睡前一小时不看发光屏幕，要看就看纸书或墨水屏
成本: 不花钱。睡前一小时放下手机，要长期对抗惯性，需要毅力。
说人话: 睡前读发光屏幕，比读纸书晚约 10 分钟才睡着。褪黑素被压低 55%。第二天生物钟往后推 1.5 小时以上，早上更困，要更久才清醒。
收益: 实验室里让同一批人两种条件轮着做（交叉试验）。睡前读发光的电子书，比读纸书入睡慢约 10 分钟（25.7 分钟对 15.8 分钟）。晚间褪黑素被压低 55%。第二天的生物钟（昼夜节律）推迟超过 1.5 小时，褪黑素开始分泌的时刻是 22:31 对 21:01。第二天早上更困，要更长时间才完全清醒。
证据等级: B
来源: 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>
备注: 人数少，是实验室里控好条件做的。按日常的手机亮度和使用时长，影响可能没这么大。手机的夜间模式管多大用，这项研究没测。
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