The Sun in Your Pocket: How Phones Disrupt Sleep

A lot of us are guilty of bringing our phones to bed with us. One study found that 65% of smartphone owners admit to checking their phone when they’re in bed. (i) But can spending time on your phone at night make it more difficult to fall asleep and stay asleep?

Blue Light

Human bodies rely on a circadian rhythm to know when it’s time to sleep and time to wake up. (ii) A circadian rhythm is a form of a biological clock that works over 24 hours, in time with the time it takes for the sun to rise and fall across a whole day.

Backlit phone screens emit blue light that can stop your body from converting serotonin to melatonin. Melatonin is a hormone that is strongly linked to your circadian sleep-wake cycle. At night time, when there is no more natural blue light, your body will switch over to producing melatonin to help you feel tired and ready to sleep. Our brains are sensitive to light. Melatonin production can be interrupted by the artificial blue light coming from your phone. (iii)(iv)

For anybody who has found it hard to get their brain to switch off at night, the lack of melatonin could be the culprit after putting their phone down. Not having enough melatonin can make it difficult to fall asleep and may cause insomnia.

Blue light from your phone screen can make it harder to get to sleep, but it can also decrease the sleep quality you can get. Research into blue light shows that it can reduce the amount of time your body spends in rapid eye movement (REM) sleep, as well as slow-wave sleep. Both types of sleep help with consolidating memories and maintaining our moods. (v)

Tips to help improve sleep

To help reduce the adverse effects that using your phone before bed can have on sleep, here are some ways to help you develop good sleep habits:

  • Use the blue-light filter: Both Android and Apple IOS use blue-light filters in their mobile devices. Look for ‘night mode’ or ‘night light’ in your phone settings menu. These will help to limit your level of blue light exposure.
  • Stop using your phone at least 30 minutes before bed: According to the National Sleep Foundation, you should aim to stop using electronic devices 30 minutes before bedtime. (vi)
  • Use an alarm clock: People usually rely on their phones to set the alarm for the morning, leading to accidentally scrolling for longer than intended. Using a separate alarm clock can help.

Using your phone before or in bed is something many of us do without giving much thought to how it affects us. To help encourage healthier sleep and a better mood during the day, avoiding screens before bedtime can make a world of difference.


  1. Heimlich, R. (2010). Do You Sleep With Your Cell Phone? [online] Pew Research Center. Available at: https://www.pewresearch.org/fact-tank/2010/09/13/do-you-sleep-with-your-cell-phone/ [Accessed 2 Apr. 2021].
  2. Reddy S;Reddy V;Sharma S (2020). Physiology, Circadian Rhythm. [online] . Available at: https://pubmed.ncbi.nlm.nih.gov/30137792/ [Accessed 2 Apr. 2021].
  3. Tosini G;Ferguson I;Tsubota K (2016). Effects of blue light on the circadian system and eye physiology. Molecular vision, [online] 22. Available at: https://pubmed.ncbi.nlm.nih.gov/26900325/ [Accessed 2 Apr. 2021].
  4. Tähkämö, L., Partonen, T. and Pesonen, A.-K. (2018). Systematic review of light exposure impact on human circadian rhythm. Chronobiology International, [online] 36(2), pp.151–170. Available at: https://pubmed.ncbi.nlm.nih.gov/30311830/ [Accessed 2 Apr. 2021].
  5. Riemann, D., Krone, L.B., Wulff, K. and Nissen, C. (2019). Sleep, insomnia, and depression. Neuropsychopharmacology, [online] 45(1), pp.74–89. Available at: https://pubmed.ncbi.nlm.nih.gov/31071719/ [Accessed 2 Apr. 2021].
  6. Sleep Foundation. (2020). Sleep Quality: How to Determine if You’re Getting Poor Sleep | Sleep Foundation. [online] Available at: https://www.sleepfoundation.org/sleep-hygiene/how-to-determine-poor-quality-sleep [Accessed 2 Apr. 2021].

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