Tammy Darcy knows what it's like to be a teenager whose world has fallen apart. Life was rosy until she hit 14 and then the shocks came, wave after wave of them. Her older sister Shona was diagnosed with a brain injury and her parents’ marriage broke down. Her grades took a nosedive and she was severely bullied in school.

Now a successful social entrepreneur, Tammy told Ella McSweeney on The Ryan Tubridy Show about her book The Survival Handbook for Girls – Everything You Need to Know about Nailing Secondary School. Tammy says the book is the kind of thing she could have done with at age 14.

"I started acting up, and then you get labels put on yourself like 'the bad kid’ or ‘the troubled kid’, or whatever the case may be. If somebody puts those labels on you and you’re 14 and you accept them, that’s who you are now."

"A lot of kids never come back from that. I hope that I did and I know lots of other people that did but I also know lots that didn’t who would have had huge potential and a lot to offer and never got to realise that."

Tammy’s new handbook focuses on girls, because that chimes with her personal experience, and where she feels her impact can be greatest, but the book can be read by boys and adults too. Tammy is a powerful cheerleader for all teenagers and she defends them against some of the old clichés people use about them.

"They are so busy, and I think we underestimate that. Teenagers are not lazy, they’re tired."

The impact of social media on stress levels in teenagers is far from just another easy soundbyte, it shows up in the data as Tammy told Ella today. "We know why teenagers, in general, do have mental health issues, anxiety and depression, because it spiked at exactly the same time as social media use spiked."

More difficult to explain is why some of the highest rates of suicide and depression in Europe are found among Irish teenage girls. Tammy says some of the problem lies in how women and girls are represented – or not represented – visually online.

"If you think of the amount of images that a teenage girl sees every day, and if they don’t see themselves represented in those images or if they feel they’re not good enough for not meeting that standard of what a woman or a young girl should look like, it’s putting them under huge stresses."

The handbook is aimed at girls in first year in secondary school and it contains advice, snippets of information and personal accounts. It’s designed to be a support for girls as they hit a vulnerable stage.

"We wanted every first-year girl who is just kind of bedding into school and starting to make friends and starting to hit those hormonal years, we wanted to make sure that they had all the information and advice that they need to get through those challenges as they arise."

Tammy Darcy says the handbook doesn’t avoid mentioning the dark times, but the tone is upbeat and positive.

"We try and address those challenges in a really positive way, so we don’t say ‘this is awful’ or ‘this sucks’ or ‘school is awful’ or ‘making friends is hard’."

"We always try and be really positive when we’re talking about things like that because there is always an answer, there’s always a way through it, there’s always something to be learnt."

You can hear more about Tammy’s story and The Survival Handbook for Girls – Everything You Need to Know about Nailing Secondary School, in the full interview above.