Specialist Advice — 14 minutes
How does smartphone use affect my sleep?
These days, our phones are with us everywhere we go. For many of us, they’re the last thing we look at night, and the first thing we turn to in the morning. But is the constant exposure to the glowing light of their screens having long term effects on our sleep hygiene? The quick answer is yes. Using an electronic device induces a state of both physiological and psychological hyperarousal. Physiologically, by increasing your cortisol (stress hormones) and body temperature and delaying melatonin secretion, and psychologically by contributing to anxiety and depressive moods.
- Physiologically: increases your cortisol (stress hormones) and body temperature and delays melatonin secretion.
- Psychologically: contributes to anxiety and depressive moods.
It’s only been a decade or so that we’ve had these screens so perpetually tethered to us, so rigorous scientific scholarship around these effects is relatively fresh. Studies related more broadly to electronic media have been around for some time — the use of TVs, computers, and such have been shown to have negative effects on sleep quality and tiredness, particularly amongst children [1]. A literature review of existing studies of the effects of screen time amongst children and adolescents in 2015 showed that between 76% to 94% of the studies conclude that screen time have clear detrimental impacts on sleep no matter the media—TV, computer or video games—though interactive viewing seems more detrimental than passive viewing like TV [2].
Smartphones, however, present a new problem. A 2018 study conducted in China studied the association between long-term mobile phone use with sleep disturbance and mental distress in several thousand technical college students.
23.5% of participants reported use of a phone of more than 4 hours per day, which increased the odds of sleep disturbance and mental distress by up to 1.5 times. More importantly, the study also showed that reduction in phone use ameliorated the issues [3].
Given that the study suggests the penetration rate of mobile phone use in China has increased from 6.7% to 96.9% since the beginning of the 21st century, with a correlated rise in time spent, the impacts of this are significant. In Quebec, from 2008 to 2018, the proportion of the population using a smart phone has risen from 13% to 73%, while 98% of the population between 18 and 34 years have a smart phone in 2018 [4].
Read more: How does internet addiction affect the body?
Why does smartphone screen exposure negatively impact my sleep?
Some of the causes of the relationship between phone use and poor sleep seem fairly straightforward. A study on adolescents from early 2019 outlines a number of potential factors shown in previous research, including:
- Longer waking hours due to device use
- Resistance to bedtime when a device is present in a bedroom
- Increased cognitive arousal, meaning an active mind and racing thoughts
- The interruption of text messages and notifications during the night [5]
The study does caution that the results of existing longitudinal studies are hampered by their self-reported nature, and the relative lack of long-term studies which include smartphone use.
Artificial light exposure itself has also been shown to have notable effects on sleep quality, largely due to how it alters the body’s production of melatonin, which effects our circadian rhythm. It is blue light, present in screens along with the other colours on the spectrum, which studies have shown to have the most impact on melatonin production. One Harvard study showed that blue light exposure suppressed melatonin twice as much as green light of comparable duration [6]. That said, blue light isn’t something to be entirely avoided, even if that were possible—in fact it can be the most beneficial during daylight hours, boosting attention, reaction times, and mood.
How can I mitigate the effects of screen exposure on sleep?
Avoid exposure to artificial light before bedtime
You should avoid exposure to bright light, particularly screens, for two to three hours before bed. This is easier said than done, of course, but most modern smartphones provide built-in tools to limit device functionality by time, allowing you to cut out notifications and temptations both close to bed time, and in the early morning. Also consider dimming the screen at night, or using the “dark mode” options available on most phones.
Consider blue-light filtering glasses
Cutting out screen time entirely may of course not be possible. One thing which may help is wearing glasses with lenses designed to filter blue light, commonly available from most optometrists. A small randomized trial in 2009 showed that those who wore blue-light blocking glasses in the three hours prior to bed had a significant improvement in sleep quality and mood [7]. A later study which focussed on teenage boys showed significant effects on melatonin suppression levels [8].
Sleep Hygiene
Instead of viewing your phone or tablet before bedtime, incorporate good sleep habits in your routine such as relaxation and abdominal breathing and be aware of sleep signals such as decreases in your body temperature. Reserve the bedroom for intimacy and sleep, and make good sleep a priority in your life, but not an obsession.
Read more: Sleep disorders and tips for better sleep hygiene
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Sources8
- Cain, Neralie, and Michael Gradisar. “Electronic Media Use and Sleep in School-Aged Children and Adolescents: A Review.” Sleep Medicine 11, no. 8 (2010): 735–42. https://doi.org/10.1016/j.sleep.2010.02.006.
- Hale, Lauren, and Stanford Guan. “Screen Time and Sleep among School-Aged Children and Adolescents: A Systematic Literature Review.” Sleep Medicine Reviews 21 (2015): 50–58. https://doi.org/10.1016/j.smrv.2014.07.007.
- Liu, Shuai, Yun Kwok Wing, Yanli Hao, Weixia Li, Jihui Zhang, and Bin Zhang. “The Associations of Long-Time Mobile Phone Use with Sleep Disturbances and Mental Distress in Technical College Students: a Prospective Cohort Study.” Sleep 42, no. 2 (March 2018). https://doi.org/10.1093/sleep/zsy213.
- “NETendances 2018 - La Mobilité Au Québec.” CEFRIO. Accessed November 2019. https://cefrio.qc.ca/fr/enquetes-et-donnees/netendances2018-mobilite-au-quebec/.
- Foerster, Milena, Andrea Henneke, Shala Chetty-Mhlanga, and Martin Röösli. “Impact of Adolescents’ Screen Time and Nocturnal Mobile Phone-Related Awakenings on Sleep and General Health Symptoms: A Prospective Cohort Study.” International Journal of Environmental Research and Public Health 16, no. 3 (December 2019): 518. https://doi.org/10.3390/ijerph16030518.
- Harvard Health Publishing. “Blue Light Has a Dark Side.” Harvard Health. Accessed November 2019. https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side.
- Burkhart, Kimberly, and James R Phelps. “Amber Lenses to Block Blue Light and Improve Sleep: a Randomized Trial.” Chronobiology international. U.S. National Library of Medicine, December 2009. https://www.ncbi.nlm.nih.gov/pubmed/20030543.
- Lely, Stéphanie van der, Silvia Frey, Corrado Garbazza, Anna Wirz-Justice, Oskar G. Jenni, Roland Steiner, Stefan Wolf, Christian Cajochen, Vivien Bromundt, and Christina Schmidt. “Blue Blocker Glasses as a Countermeasure for Alerting Effects of Evening Light-Emitting Diode Screen Exposure in Male Teenagers.” Journal of Adolescent Health. Elsevier, October 3, 2014. https://www.sciencedirect.com/science/article/pii/S1054139X14003243.
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