Watch: 'Life isn't perfect': Head girl's brave depression speech

A Christchurch head girl has bravely revealed a personal battle she'd been dealing with to fellow students during her farewell speech.

Jem Vaughan also took the opportunity to remind students at St Margaret's College in Christchurch the damage that can be caused by social media and reminded them it's often only a person's "highlights reel" that's portrayed.

"I know I've heard hundreds of times social media is destroying teens but it does have truth behind it. Social media makes it easy for us to compare lives and we forget that what we see is just a highlights reel.

"When we wear rose-tinted glasses when we look at everyone else's lives but then we take them off when we look at ourselves."

In her heartfelt speech, Vaughan said she had attended "the best school ever" as well as having "the best friends" and a supportive family.

But despite all of that, she found herself in a dark place earlier this year.

"At the beginning of the year, I actually found myself really unhappy. I was tired all the time, I'd lost my appetite, I was crying, a lot, all for no reason."

She started talking to someone about it and in June was diagnosed with clinical depression.

"Looking back it made a whole lot of sense. I had been really sad for quite a while and feeling guilty about it, angry at myself, my problems seemed so trivial so why was I unhappy.

"I guess that made me realise a few important things this year. The first one being that mental illness doesn't discriminate. There isn't always an identifiable cause for it.

"Sometimes, as it was for me, it's a mixture of genetics and brain chemistry and other complicated stuff that's hard to predict or pinpoint."

However, most importantly, she said, she realised there was no "direct path or checklist that will lead you to maximum happiness".

"Trust me, I tried to follow the path and you don't feel any different from everybody else on all the other paths."

Everybody had their own story and she reminded them that it was okay if there's wasn't perfect.

"Believe it or not, nobody has life sorted. Everyone in this room has stories, good and bad, obvious and hidden.

"Lives really can't be ranked or graded, girls. Everyone has their highs and their lows so for that reason your own, messy, non-linear, in-perfect life is the best one for you, I promise. But also in saying that it's really not okay if life is making you unhappy.

"Girls, whatever sadness anxiousness or worry looks like for you please always remember you're so incredibly valued and loved and you're always enough just as you are."