Is our sleep disturbed by the use of smartphones?
The mobile phone is everywhere. You have surely noticed it, and for good reason, there is very likely one close to you, perhaps even in your hand, at this moment! It has now become an integral part of the lives of many of us. A very practical technology in daily life, whether for personal needs or work, it accompanies us all day long and even makes its way into the bedroom to spend a sweet night in our company and sleep peacefully! But for us, what about the quality of our sleep with this luminous companion at hand?
If this little gem of progress is increasingly present in our lives, we can still wonder what its impact is on our health. What are the effects of mobile phone use on our sleep? Will our smartphone's GPS guide us on the road leading to sleep? Nothing is less certain!
Responding to the irresistible call of blue light at night
Or when your night resembles that of operators working in telephone exchanges from the last century! Indeed, we use our mobile phone a lot during the day, but also in the evening, at night, and this is increasing. Why? To get informed, to entertain ourselves, but also to stay connected to our work, read our emails, or fight against a feeling of loneliness by browsing social networks in search of a bit of virtual company. This nighttime company actually takes on a particular color: blue. In the evening or at night, your phone does not tell you "the blue words," as Christophe sang, but it certainly sends blue to your eyes. Scientists have looked into this blue light.
Thus, a study by INSERM[1] (National Institute of Health and Medical Research) reveals to us that "the effect of light on the biological clock depends on its spectrum and will be all the more important as it is rich in blue wavelengths." You don't see what it's about? To put it simply, let's say that our eyes perceive all kinds of lights, which have different effects on our body. The lights from mobile phones are those that our eyes filter the least well, of the same type as those from screens or so-called "LED" lights. The effects of blue light from mobile phones are harmful: sleep disorders and disruptions to the circadian system (the body's biological rhythm). Indeed, the photoreceptors in our eyes perceive this turquoise blue light as a stimulant, sending a "waking message" to our biological clock, while the surrounding darkness tells it that it is time to sleep (as noted by Dr. Sylvie Royant-Parola on pages 10-11 in a report from INSV[2] for the World Sleep Day 2016). The use of mobile phones harms sleep quality by decreasing melatonin secretion (by 4 to 6 times less) and, conversely, increasing sleep onset latency.
The message left by blue light on the sleep answering machine the next morning is unequivocal: fatigue!
Which plan to choose for unlimited sleep?
Not responding in time to the call of sleep and risking seeing "Mrs. Insomnia" leave a message on your biological answering machine is the consequence of a form of screen addiction, particularly to mobile phones. Numerous studies[3] report, in different countries or environments, sleep onset difficulties related to smartphones. The effect of using a mobile phone at bedtime results in a decrease in sleep duration and an increase in sleep onset latency as shown by a study conducted in China[4], and its conclusion is very clear: "Restricting mobile phone use close to bedtime reduced sleep latency and arousal before sleep and increased sleep duration and working memory."
No mobile phone at bedtime is therefore synonymous with a good plan for quality sleep!
There is a strong dependence, for various reasons, on the use of mobile phones in the evening or at night, "more than a third of the French use their computer, tablet, smartphone in bed in the evening," according to a survey[5] from the National Institute of Sleep and Vigilance, with the finding of a harmful effect of mobile phone use on sleep quality. So, it is not just the blue pains (the blue lights, not the blue words of Christophe, you will have understood!) that alter sleep quality; there is also this heightened vigilance, this attention, this expectation of communication created by the smartphone that disrupts your night. However, know that a 2020 study conducted in Sweden[6] shows that there would be no harmful effect from using the smartphone as a simple phone: spending hours with it glued to your ear is risk-free, except for perhaps having a cramp in your arm. That's already something for all our nocturnal operators addicted to the phone! Moreover, it is good to know that you can download blue light filter apps on your mobile phone. These filters help limit the harmful effects of its screen. Progress cannot be stopped!
In conclusion, it is better to remain reasonable in our face-to-face with screens before and at bedtime if we want to avoid missing the sleep train that, unlike you, will not respond to your desperate message on its voicemail to let you board! Prefer a book or any other activity without blue light...
Sources:
[1] Chronobiology: the 24-hour clock of the organism, "INSERM" website, 2021 [2] Sleep and new technologies, "INSV" website, 2016 [3] Effect of smartphone usage on quality of sleep in medical students, Nida Nowreen, Farhana Ahad, "National Journal of Physiology, Pharmacy and Pharmacology", 2018 [4] Effect of restricting bedtime mobile phone use on sleep, arousal, mood, and working memory: A randomized pilot trial, Jing-wen He, Zhi-hao Tu et al, "Journal Plos One", February 2020 [5] Sleep and new technologies, "INSV" website, 2016 [6] Long-term effect of mobile phone use on sleep quality: Results from the cohort study of mobile phone use and health, Giorgio Tettamanti, Anssi Auvinen et al, "Environment International", 2020
