Teenagers who use their mobiles late at night sleep worse than those who don't, leading to poorer mental health, reduced coping and lower self-esteem, West Australian researchers have found.
Students were asked what time of the night they received or sent text messages and phone calls, as well as their perceptions of their sleep quality, in the four-year study by Murdoch and Griffith universities.
The study surveyed 1100 students from 29 schools, starting in Year 8 and following them until Year 11.
Head researcher Lynette Vernon said mobile phone use became a problem when prioritised over other aspects of life, such as time for sleep.
"We found that late night phone use directly contributed to poor sleep habits, which over time led to declines in overall wellbeing and mental health," Dr Vernon said.
In Year 8, about 86 per cent of the students had a mobile phone, increasing to 93 per cent in Year 11.
For students who owned a mobile phone in Year 8, only 36 per cent said they never sent or received text messages or phone calls after lights out on school nights.
This decreased to about 22 per cent in Year 11.