A quarter of WA teenagers are spending more than four hours a day online using non-school-related websites, according to a survey.
The Tech Use and Safety Project, which surveyed 753 high school students, found a quarter of 13 to 15-year-olds spent more than four hours a day on activities such as social media, watching videos and playing games. On weekends, the figure jumped to 40 per cent.
The study by Edith Cowan University's Sellenger Centre comes ahead of worldwide Safer Internet Day on Tuesday.
Students who spent more time on social networking sites such as Facebook were more likely to report symptoms of depression and anxiety and were also more likely to be victims of cyber bullies.
Sellenger Centre associate director Julian Dooley said it was encouraging that teenagers appeared to be more aware of online risks, with 85 per cent saying privacy was important and 79 per cent saying they would tell a friend if they were contacted by a stranger online.
This could be a result of cyber safety campaigns, he said.
But Dr Dooley said there was work to be done, with 24 per cent of teenagers saying they had shared their social networking passwords with others and 41 per cent admitting they had shared personal details, such as mobile phone numbers, online.
Dr Dooley said it was important for schools and parents to give children strategies for online safety when they were unsupervised.
"One of the most important things (for parents to do) is have discussions about safety strategies which are appropriate for the types of technology they are using," he said.
"Kids are saying privacy is really important, but half of them are sharing personal information, like mobile phones and email addresses, with everyone on their Facebook account, which is hundreds and hundreds of people, without realising the implications."
He said removing technology if children or teenagers experienced problems online was ineffective as teenagers would be more likely to hide problems for fear of losing access to the internet.
Child and adolescent psychologist Michael Carr-Gregg said parents needed to find their digital spine and "set limits and boundaries around the use of this technology".
DID YOU KNOW? 91% Of 13 to 15-year-olds have a mobile phone. More than half of them use it to go online.