A UNIGE study shows that reducing smartphone use
in the evening significantly increases teenagers' sleep
and improves their academic performance.
What impact do screens have on teenagers' sleep? A 2021 study by the University of Geneva (UNIGE), conducted in secondary schools in collaboration with the Department of Public Education, Training and Youth (DIP) of the Republic and Canton of Geneva, shows that strict parental rules on smartphone use in the evening are associated with a significant increase in sleep duration and better academic performance. These findings can be found in Discover Public Health.
Sleep plays a crucial role in cognitive and emotional functions. It contributes to memory consolidation, alertness, and emotional stability. Healthy sleep also prevents the early onset of psychiatric disorders such as anxiety and depression. However, adolescents are sleeping less and less, often well below the 8 to 10 hours of sleep recommended for their age by the American Academy of Sleep Medicine (AASM), the global authority on the subject.
According to a 2020 study by Unisanté, 12 times more 14-year-olds spent more than four hours a day in front of a screen than in 2012 in Switzerland.
According to a 2020 study by Unisanté (Lausanne), in Switzerland, 14-year-olds were 12 times more likely to spend over four hours a day in front of a screen in 2020 than in 2012. However, this excessive exposure has negative consequences on the duration and quality of sleep. Screens delay bedtime by taking up precious time, but also by stimulating attention and emotions, making it harder to fall asleep. While having screens in the bedroom is known to be a contributing factor, few studies have explored the effects of specific parental rules on sleep.
Strict rules are the most effective
The UNIGE team analysed the responses of 329 students aged 13 to 15. They were asked to complete a questionnaire about their sleep habits and their parents' rules regarding screen use. The results show that students subject to the strictest rules – no phones in their bedrooms and no use in the evening – sleep significantly longer. On average, the sleep gain is 40 minutes per night.
''This is considerable, given that this population group needs about 9 hours of sleep and often only gets 7 to 8. Each week, these 40 minutes represent almost an extra night's sleep,'' says Virginie Sterpenich, a researcher in the Department of Basic Neuroscience at the UNIGE Faculty of Medicine, who led the study. Other types of restrictions, such as limiting daily screen time or setting a bedtime, do not have a significant effect on sleep duration.
Multiple benefits
The study does not stop at sleep duration. It also shows that young people who sleep more perform better at school. "Parents therefore have a key role to play. Their involvement directly influences their children's health and success. They need to be encouraged in this direction. This framework must be established before the age of 15, beyond which bad habits are more difficult to correct,'' says Kevin Mammeri, a doctoral student in the Department of Basic
Neuroscience and first author of the study.
The next step, already underway in schools, is to offer awareness workshops and practical tools to students whose sleep is impaired. "Many stay in bed with their phones, with no clear distinction between where they sleep and where they surf the internet," notes Virginie Sterpenich. "Changing this habit would be a good step towards healthy sleep."
