It's natural for children to go through a shy, sullen or non-communicative stage during their teenage years - after all it's a time of great upheaval and change.
And for the most part, the best thing parents can do is be accepting and non-judgmental to help them through this tricky time. But how can you tell if low confidence is a serious problem for your teen? And if it is, what can parents do?
We spoke to psychologist Emma Kenny for some advice on boosting teenagers' self confidence.
Is your teen under-confident?
"Signs that your teen is struggling with confidence issues can be hard to recognise as often teens do many of them anyway," explains Emma.
"But generally, if you notice that they tend to isolate themselves, spend a lot of time in their bedroom, not socialising and seem to avoid going out with friends it may be because they've got serious problems with self confidence.
"On the other hand, if you notice them indulging in risky behaviour such as going out and getting very drunk, this could be the sign of a problem too.
"High risk is often caused by low confidence."
She adds: "Another sign is difficulty communicating, both with you and with their friends and peers. If teens are worried about how they're perceived and aren't confident in their opinions they can find it difficult to vocalise their thoughts."
Confidence isn't just something you grow into
Emma explains that some people just don't have the 'confidence gene' and that expecting all children to grow out of any shy or awkward phase they enter isn't always realistic.
"Confidence is something teenagers need to work on. They might not just grow out of it so it's not worth just accepting it and waiting for that to happen.
"Instead you have to work on it and begin to behave confidently even when you aren't feeling it to start to make that change."
What can parents do?
Parents are key to helping their teen start to make the changes they need to boost confidence, says Emma.
"Environment is very important. Home life is really influential so parents need to work to make an environment that feels safe, where open communication is encouraged - a real haven.
"If teens are made to feel that they can say what they think without being told off, they are less likely to self-censor. Safety equals confidence.
"If parents aren't so confident themselves, it can also be something they can work on together with their teen, making some mutual goals and helping each other to achieve them."
Emma reminds us that being a teenager is pretty hard work. It's a time when you're deciding who you want to be and who you are - becoming a whole person. Add to that hormones, gaining experience in new areas such as going out work work and starting their first romantic relationships and it's not surprising that it's a difficult time to be creating yourself. Plus, there's worries about your appearance to add a whole layer of body confidence issues.
"Parents can help by encouraging their teen to be aspirational. Help them identify strengths they admire in others and would like to have themselves," says Emma.
If you're good at something it stands to reason that you'll be more confident at it.
"Encourage your teens to play to their strengths and give them approval and affirmation around it. Praise is vital to boost confidence.
"Society is a very conformist system and there's a pressure on youngsters to be good at certain things deemed important by their circle of friends, But what they think is important may not be what your teen excels at, so help them re-evaluate what they want to achieve bearing in mind the skills and talents they are best at."
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What can teenagers do?
Emma admits that there's only so much parents can do. Teens have to want to improve their own confidence too.
"Start by setting smart targets – small, achievable, timed goals that give you something to focus on and something that you can recognise when you've ticked it off. This gives you a way of celebrated success.
"The second tip really would be 'fake it til you make it'. Mimic confident people on TV and play the character. Remember, part of being confident is the way other people treat you so if you act like you are confident (even if you're not) they will respond to that and it will create a positive cycle."
"And lastly, and it's difficult - don't compare. As much as possible stay away from Facebook.
"Try to use the net as a resource for learning rather than emotions. Try to detox from that. Every now and then give yourself a reality check – if you have the time to update your status, you have time to do something else that will ultimately make you feel better.
"Finally - give yourself a break. It's OK. It's difficult for everyone."
Emma Kenny is working with ACUVUE Contact Lenses to highlight awareness lens availability for children and young people, after her son's strong glasses prescription left him seriously lacking in confidence.
Emma says: "It made such a different to him and most parents and children don't realise that they have these options. For many, contacts are less cumbersome and give freedom and a self-esteem boost."