Sleep deprivation is exacerbating mental health problems among teenage girls in Scotland, experts have said.
Research has shown almost a third of young people experience problems nodding off which has a negative impact on both mental and physical health.
But girls age 15 and over in particular are experiencing high levels of pressure in their lives which has contributed to anxiety and nervousness.
Leaders of the recent study said the picture is complex.
The research, led by Glasgow University and commissioned by NHS Health Scotland, surveyed school-age children in 2018. It found that the proportion of young people reporting sleep difficulties more than once a week increased from 23% in 2014 to 30% in 2018.
Some areas of wellbeing did show improvement - such as a reduction in substance, alcohol and tobacco use as well as healthier eating habits and 85% reporting high life satisfaction.
However, researchers found that just over a third (37%) of adolescents were classified as having low mood (33% boys, 41% girls) and 14% were at risk of depression (11% boys, 17% girls).
Lead author of the study Dr Jo Inchley, from Glasgow University, said a number of factors could influence mental health, including social media, but that sleep was significantly important for physical and mental wellbeing.
She told BBC Scotland: "There is a range of issues there that we need to understand better and provide support for young people - girls in particular.
"When we speak to young people what we do find is a lot of older girls reporting high levels of pressure from schoolwork but also things in their lives - managing their friendships, managing their relationships at home, thinking about their future careers, thinking about their body image and their health.
"So all these things may be contributing to higher levels of anxiety and feelings of nervousness that we see in our research."
Turning to fathers for help
Previous studies have linked sleep problems among adolescents to electronic devices and social media.
And while the latest research had similar findings, Dr Inchley said it showed children reporting more support from their families in some cases - specifically girls feeling able to talk to their fathers about problems.
Meanwhile, Dr Justin Williams of the Royal College of Psychiatrists Scotland said that affluence and supportive families were an "important source of resilience".
He said: "The increasingly rich media diet offered to our young people today often causes problems because they consume too much or consume the wrong stuff.
"It can displace family life, physical activity and even just sleep. And some young people, especially those with mental health problems, are highly vulnerable to these negative effects."
Dr Rory Mitchell, public health intelligence principal at NHS Health Scotland, which funded the study, highlighted that children from wealthier families tended to report better health and wellbeing.
He said there was a need for "a continued focus on tackling health inequalities in Scotland."
The 2018 Health Behaviour in School-aged Children involved 5,286 pupils, covered areas such as sleeping habits, time spent online, physical activity and school and home life.
Data was collected from surveys with 11, 13 and 15-year-olds in Scotland.
- On weekdays the average length of sleep was 8.3 hours for 13-year-olds and 7.8 hours for 15-year-olds
- The recommended sleep for teenagers is eight to 10 hours each night
- Under one in five (17%) adolescents in Scotland meet the recommendations for exercise
- Young people playing computer games on weekdays has "substantially" increased - 22% to 42% among girls and from 53% to 71% among boys
- 92% of 15-year-olds keep their smartphones in their bedroom at night
- 95% of young people said they own a smartphone with a connection to the internet
- Vigorous physical activity was found to be higher among boys than girls
- The proportion of adolescents who reported eating fruit or vegetables every day was 35% and 36% respectively.