Teenagers’ late-night mobile phone use is harming their sleep and potentially their mental health, say researchers who advised that “physical boundaries” be set over use of such devices in the bedroom.
A longitudinal study of 1,101 Australian high school students aged between 13 and 16 found poor-quality sleep associated with late-night texting or calling was linked to a decline in mental health, such as depressed moods and declines in self-esteem and coping ability.
Lead researcher, Lynette Vernon of Murdoch University in Perth, said her findings were evidence of the need for curfews for teenagers to be established around use of devices in their bedrooms. Adolescents who used their phones as alarms should replace them with clocks in order to maintain “physical boundaries”, she said.
Vernon said mobile phones had become entrenched in young people’s lives, and many did not have their use restricted. She pointed to international research that found about 80% of the young had access to a mobile phone.
The former high school teacher said she had observed her own pupils coming into the classroom tired. “I noticed it was affecting their performance – that was a few years back, too.”
Though the link between late-night phone use and sleep, and between sleep and wellbeing, had been established in previous research, this was the first study to assess all three together, she said.
“It’s important to have the research to translate to parents and teachers, who probably haven’t experienced to the same extent what kids are doing.
“If you’re finding your son or daughter is more moody and not coping at school, you often put that down to adolescence – but it could be as simple as them not sleeping at night.”
The study specified sending and receiving messages and/or phone calls, so did not distinguish between mobile phones and smartphones or social media.
Students in Year 8 who reported higher levels of night-time mobile phone use also reported higher levels of depressed mood and externalising behaviour and lower self-esteem when surveyed one year later.
Few teenagers indicated that they never used their phone after lights out, and on average, younger teenagers’ healthy mobile phone habits became more problematic as they advanced through high school.
“The outcomes of not coping – lower self-esteem, feeling moody, externalising behaviours and less self-regulation, aggressive and delinquent behaviours – the levels increase as sleep problems increased.”
Teenagers who reported “constantly texting into the night” said when surveyed a year later, the problem had worsened. “It’s escalating – they’re highly invested in it … Some kids are staying up until 3am.”
The study, Mobile Phones in the Bedroom: Trajectories of Sleep Habits and Subsequent Adolescent Psychosocial Development, was published in the Society for Research in Child Development on Tuesday.
Teenagers need eight to 10 hours of sleep for healthy development, Vernon said.
Phones disrupted sleep in two ways, with the bright light from screens disrupting natural circadian rhythms, and messages received before sleep spiking “cognitive and emotional arousal”, said Vernon.
Education was the best prevention, Vernon said, and it was most effective if it began before children were given their first mobile phone. “As a mother of teenage kids, I think you’ve got to negotiate, and negotiate early.”
Parents could also set a good example by demonstrating good habits around phone use themselves. “Back when they’re aged seven to 10, you have to role model – you put your phone in a basket at night, it doesn’t go into your bedroom, it becomes normalised in the household and you have a much easier job.”