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, or even in your hand, at this very moment! It is now an integral part of the lives of many of us. A very practical technology for daily use, whether for personal needs or work, it accompanies us all day and even invites itself into the bedroom to spend a gentle night in our company and sleep peacefully! But for us, what about the quality of our sleep with this bright companion within reach?
If this little gem of progress is increasingly present in our lives, we can still wonder what its impact on our health is. What are the effects of mobile phone use on our sleep? Will the GPS of our smartphone guide us on the road leading to sleep? Nothing is less certain!
Answering the irresistible call of blue light at night
Or when your night resembles that of operators working in telephone switchboards of the last century! Indeed, we use our mobile phone a lot during the day, but also in the evening, at night, and increasingly so. Why? To get information, entertain ourselves, but also to stay connected to work, read emails, or fight against a feeling of loneliness by browsing social networks in search of some virtual company. This night company takes on a particular color: blue. In the evening or at night, your phone does not say to you "les mots bleus," as Christophe sang, but it does send blue to your eyes. Scientists have studied this blue light.
Thus, a study by INSERM1 (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." Don’t see what this means? Simply put, 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 of the circadian system (the body's biological rhythm). Indeed, the photoreceptors in our eyes perceive this turquoise blue light as a stimulant sending a "wake-up message" to our biological clock, while the surrounding darkness tells it to sleep (as noted by Doctor Sylvie Royant-Parola on pages 10-11 in a dossier from INSV2 for the Sleep Day 2016). Using a mobile phone harms sleep quality by decreasing melatonin secretion (by 4 to 6 times less), and, conversely, by 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 answering the call of sleep in time and risking seeing "Madame Insomnia" leave a message on your biological answering machine is the consequence of a form of screen addiction, particularly to mobile phones. Numerous studies3 report, in different countries or environments, difficulty falling asleep 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 China4, whose conclusion is very clear: "Restricting mobile phone use near bedtime reduced sleep latency and pre-sleep arousal 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 using the mobile phone in the evening or at night; "more than a third of French people use their computer, tablet, smartphone in bed in the evening" according to a survey5 by the National Institute of Sleep and Vigilance, with the observation of a harmful effect of mobile phone use on sleep quality. So it’s not just the blue woes (the blue lights, not Christophe’s blue words, as you understand!) that impair sleep quality, but also this increased alertness, this attention, this expectation of communication created by the smartphone that disrupts your night. Know, however, that a 2020 study conducted in Sweden6 shows that there would be no harmful effect from using the smartphone as a simple phone: spending hours with it pressed to your ear is risk-free, except maybe for having a cramp in your arm. That’s something for all our nocturnal operators addicted to the phone! Moreover, it is good to know that you can download blue light filters via applications on your mobile phone. These filters help limit the harmful effects of its screen. Progress never stops!
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 which, itself, will not answer 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" site, 2021 [2] Sleep and new technologies, "INSV" site, 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" site, February 2020 [5] Sleep and new technologies, "INSV" site, 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