Does your phone keep you awake?
What the research found, how to do it, and every source the episode cites.
The verdict
Worth a two-week try.
- When
- it's 30 min to bedtime
- Then
- turn your phone off
§ 01 · The protocol
§ 02 · Transcript
- The question
Does your phone keep you awake?
- How it works
Most people blame the light. Your body clock is a timer in your brain, and light keeps it on schedule. In the evening, the clock releases melatonin, which tells your body that night has come. Bright light holds that signal back, so sleep comes later. A phone's light does this, but only a little. The bigger problem is time. Every minute you scroll in bed is a minute you're not asleep.
- The research
In a small trial, poor sleepers took half an hour to fall asleep. One group turned their phones off thirty minutes before bed. Four weeks later, they took eighteen minutes. The other group barely changed.
- The protocol
Here's how to run it. Turn your phone off thirty minutes before bed, so one more video can't start. Night mode isn't enough, because it only changes the light.
- The verdict
So your phone can keep you up, mostly through time, not light. Turning it off early is worth a two-week try. Track your sleep with Anvilus.
§ 03 · In the sources' words
“Restricting mobile phone use before bedtime for four weeks was effective in reducing sleep latency”
“our results can be interpreted as supporting the displacement hypothesis, i.e., that the time spent on screens displaces sleep”
“in most people it must be reset by a small phase advance shift each day”
“we observe dose-dependent increases in sleep latency, reductions in melatonin concentration and delays in melatonin onset as a function of melanopic irradiance”
“the evening melatonin increase was attenuated in both smartphone conditions”
“Thirty-eight participants were randomized to either an intervention group (n = 19), where members were instructed to avoid using their mobile phone 30 minutes before bedtime, or a control group (n = 19)”
§ 04 · Sources
- He JW, Tu ZH, Xiao L, Su T, Tang YX. Effect of restricting bedtime mobile phone use on sleep, arousal, mood, and working memory: a randomized pilot trial. PLoS One 2020;15(2):e0228756
- Hjetland GJ, Skogen JC, Hysing M, Gradisar M, Sivertsen B. How and when screens are used: comparing different screen activities and sleep in Norwegian university students. Front Psychiatry 2025;16:1548273 (cross-sectional; Gradisar lists WINK Sleep and Sleep Cycle AB affiliations)
- Schmid SR, Höhn C, Bothe K, et al. How smart is it to go to bed with the phone? The impact of short-wavelength light and affective states on sleep and circadian rhythms. Clocks Sleep 2021;3(4):558–580
- Duffy JF, Czeisler CA. Effect of light on human circadian physiology. Sleep Med Clin 2009;4(2):165
- Eto T, Higuchi S. Review on age-related differences in non-visual effects of light: melatonin suppression, circadian phase shift and pupillary light reflex. J Physiol Anthropol 2023;42:13
- Revell VL et al. Advancing human circadian rhythms with afternoon melatonin and morning intermittent bright light. J Clin Endocrinol Metab 2006;91(1):54–59
- Schöllhorn I, Stefani O, Lucas RJ, et al. Melanopic irradiance defines the impact of evening display light on sleep latency, melatonin and alertness. Commun Biol 2023;6:228
- Höhn C, Hahn MA, Gruber G, et al. Effects of evening smartphone use on sleep and declarative memory consolidation in male adolescents and young adults. Brain Commun 2024;6(3):fcae173
- Efficacy of blue-light blocking glasses on actigraphic sleep outcomes: a systematic review and meta-analysis of randomized controlled crossover trials. Front Neurol 2025;16:1699303
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