One in six Kiwi 15-year-olds is now online for more than six hours a day, an international survey has found.
The Programme of International Student Assessment (PISA) tested 540,000 15-year-olds across 73 countries, including 4453 in New Zealand, mainly on their educational performance.
Its latest report, covering the students' personal wellbeing in 2015, shows that Kiwi 15-year-olds classed as "extreme" internet users because they are online outside school hours on weekdays for at least six hours a day have almost trebled from 6.1 per cent in the last survey in 2012 to 17.3 per cent.
Their schoolwork is suffering: 31 per cent of the "extreme" group had skipped a day's school in the previous fortnight, compared with 15 per cent of "moderate" users (1-2 hours a day).
But Netsafe director Martin Cocker said time spent online was actually less important than what the teens were doing online.
"Where what they are doing online is harming their relationships, their education, affecting their sleep, absolutely that's when you need to intervene," he said.
"But if your child is doing well at school and has good, solid relationships, then I would say don't worry about how much time they are spending on the internet."
Overall the survey has found that Kiwi 15-year-olds average 163 minutes online outside school each weekday, up from 98 minutes in 2012. The times are almost identical for girls (165 minutes) and boys (161 minutes).
We have leapt from below the 102-minute average of the 35-nation Organisation for Economic Cooperation and Development (OECD) in 2012 to well above the 146-minute average now - probably because of the dramatic spread of smartphones.
The teens are not just doing their homework. More than four-fifths of the girls (81 per cent), and 77 per cent of boys, say they are chatting online almost every day - both much higher than the OECD averages.
Most of the boys (55 per cent), and 15 per cent of the girls, are playing online games - internationally about average.
Majorities of both boys (57 per cent) and girls (61 per cent) admitted to being hooked, agreeing: "I really feel bad if no internet connection is possible."
The latest survey confirms others that have found very high rates of bullying in New Zealand. More than a quarter (26 per cent) of Kiwi 15-year-olds say they get bullied at least a few times a month, more than any other OECD nation except Latvia.
Kiwi teens are the most likely in the OECD (17 per cent) to agree: "Other students made fun of me."
They are the fourth-most-likely (7 per cent) to agree: "I got hit or pushed around by other students."
They feel unsupported by teachers: 39 per cent of Kiwi students said teachers ridiculed them in front of others at least a few times a year, more than in any other OECD nation except Britain (41 per cent).
Youthline director Stephen Bell said many young people over the years had told him their teachers mocked them.
"They feel that control in this classroom is through put-down," he said.
"There are some great teachers. I also think some struggle with the dynamics of the classroom."
Perhaps partly because of this, Kiwi 15-year-olds are the most likely in the OECD to agree: "Even if I am well prepared for a test I feel very anxious."
The biggest factor driving that anxiety was teachers who "give me the impression that they think I am less smart than I really am". Exactly half the Kiwi teens sometimes felt that about their teachers, the seventh-highest of the OECD nations.
However, a more positive factor was that the Kiwi kids were also highly motivated: 70 per cent agreed, "I want to be one of the best students in my class." That was 12th-highest in the OECD.
Kiwis are no longer more likely than others to do "vigorous" physical activity that makes them sweat and breathe hard: 26 per cent of the Kiwis had done this outside school for at least 20 minutes on at least five days in the past week, 17th-equal out of 35 nations and almost identical to the OECD average of 26.2 per cent.
But Kiwis are still slightly more likely than average to agree, "I feel like I belong at school" (74 per cent, average 73 per cent).
'I'm online probably like the whole day'
West Auckland schoolgirl Gabby Tatu Natiso says she is online on her smartphone "probably like the whole day".
"I'm always on. I can't live without being on my phone and social media," she said.
Gabby, who turned 16 on April 6, has a busy life. She babysits her 2-year-old brother and two nephews aged 1 and 4 most nights when their parents are at work; she plays netball, volleyball and touch; and she is a regular at church and at the Zeal youth centre in Henderson.
It's just that she does all those things while also constantly checking Instagram and Snapchat.
"I try to check my phone in between [sports] trainings," she said.
"I go to church but I always have my phone on.
"She has about 20 minutes of homework a night, which usually gets left till "the last minute" at night or early the next morning.
"When it comes to homework, I get really distracted really fast because even if I put my phone somewhere far, and my ringtone goes off, I'd end up running to it and not finishing off my work," she said.
Like many Kiwi kids, Gabby has been bullied. It was so bad at her intermediate school and in Years 9 and 10 that she sometimes went to school only once or twice a week.
"My parents would think I was going to school, but I'd just go somewhere else and wait till school finishes and then go home," she said.
"It was just like mocking and teasing, also because how I was, what colour I was. I'm Samoan/Niuean/Maori, but it was brown people mocking me."
However, she has now put a stop to it.
"I was the person who would let them stand over me and get away with the stuff they were doing - until the day I just got sick of it and I stood up for myself," she said.
"And they were, 'Oh my gosh, she's a different person!' And then they stopped from then."