# Screens: it's the arousal, not the blue light

The search for novelty is what disrupts sleep. Boring content is fine.



## Takeaways

- Boring content only before bed.

- No feeds/games in bed.

- Phone away from the bed; log screen-off time.



What's dangerous about your screen is not primarily the blue light — it's the arousal associated with the search for novelty. Feeds, games, puzzles, engagement, 'the next thing'. In-bed social media use is tied to insomnia symptoms and anxiety; phone use after lights-out to later bedtimes and fatigue. Even having a device accessible in the bedroom doubles the odds of inadequate sleep in youth.

Blue light is real but smaller: a light-emitting reader before bed delayed melatonin and morning alertness versus a printed book. Galpin watches a giant TV before bed and sleeps great — because it's a dull documentary. His wife reads and wakes up because of what she reads.

Recommendation algorithms are now tuned by AI to keep you scrolling, including at 11 pm. You are wired for novelty; the only real defence is deciding you care about tomorrow more than the next reel — and keeping the phone out of reach.



## Sources

- "To sleep, perchance to tweet": in-bed electronic social media use and its associations with insomnia, daytime sleepiness, mood, and sleep duration in adults (Bhat S, Pinto-Zipp G, Upadhyay H, Polos PG, 2018)

- Bedtime mobile phone use and sleep in adults (Exelmans L, Van den Bulck J, 2016)

- Association between portable screen-based media device access or use and sleep outcomes: a systematic review and meta-analysis (Carter B, Rees P, Hale L, Bhattacharjee D, Paradkar MS, 2016)

- Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness (Chang AM, Aeschbach D, Duffy JF, Czeisler CA, 2015)

- The inner clock — blue light sets the human rhythm (Wahl S, Engelhardt M, Schaupp P, Lappe C, Ivanov IV, 2019)

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Educational summary of published research, not medical advice. Screening scores are not diagnoses. If a score is elevated or you feel unwell, talk to a clinician.

SleepShred for iPhone: https://apps.apple.com/app/id6802040541