Julia Harris was busy tidying her daughter’s bedroom when she found a diary she suspects was deliberately left out for her to see.

Inside, 10-year-old Rosie had written that she often thought about suicide, although she didn’t think she would actually do it. Harris, a university lecturer from Yorkshire, knew her daughter had become increasingly anxious, both about friendships and school, sometimes refusing to eat in the mornings. But she hadn’t realised quite how bad things had got.

The next shock, however, was that Rosie’s symptoms weren’t bad enough to warrant help from NHS England’s child and adolescent mental health services (CAMHS). In fact Rosie’s case wasn’t deemed urgent enough even to reach the waiting list.

“When I found that diary, I felt completely at sea,” Harris says. “It’s a horrible thing to think that your child is feeling [that way], and I immediately went to where I thought support would be. If it wasn’t for the school and other parents, I would feel completely alone.”

Across Britain, thousands of families like Harris’s are supporting young people through what has been dubbed an “epidemic of anxiety”. Warning signs in children range from excessive clinginess or tearfulness to persistent worrying and negative thoughts, avoiding going out, angry outbursts, and trouble eating or sleeping. One study by researchers at University College London found diagnoses of anxiety disorder in 18 to 24 year olds trebled between 2008 and 2018, and it is estimated up to 19% of children and young people are affected.

Lockdown was an anxious time for many families but Stevie Goulding, co-manager of the mental health charity Young Minds’ parent helpline, says some children struggled to readjust to the busy outside world once it was over. Now mental health services can’t keep pace with demand. “What we hear time and time again is ‘the waiting list is very long, what do I do in the meantime?’” says Goulding.

Stress can be healthy in small doses, teaching children the skills to cope with setbacks, says NHS consultant clinical psychologist (and author of How to Have Incredible Conversations with Your Child) Prof Jane Gilmour. But if a child seems persistently overwhelmed and stressed, that is a cue to investigate, checking that they’re not over-scheduled or struggling academically. If the anxiety is about socialising, ask about bullying or specific incidents preoccupying them. “But if you have a child who is persistently anxious – about everything, or something specific – and they’re persistently fearful for a number of weeks, I think it’s time to seek professional help,” she says.

In the meantime, Gilmour advises getting children to write down or draw their worries as they occur, but then set those fears aside to review with a parent at a set time every day. Parents can help children see how worries fade over time, or discuss ways of coping with scary situations. Letting children avoid these – say, by staying off school – merely risks reinforcing the idea that there’s something to be scared of, she says. “What you need to convey is that you know they find this tough, but you’re confident they can manage and you will help them figure it out. We have to be in school to feel the anxiety peak and decrease, because we know it will decrease if we’re in the situation long enough.”

Young Minds’ Goulding recommends teaching children to recognise early warning signs of a panic attack such as a tight chest or clammy hands, and then to self-soothe when they feel one coming on using the “five senses” technique.

Some parents will find pushing an anxious child beyond their comfort zone upsetting, perhaps especially if they are anxiety-prone themselves. Prof Sam Cartwright-Hatton is a patron of the charity Anxiety UK and clinical child psychologist at the University of Sussex, currently researching anxiety within families. Children are twice as likely to suffer if their parents do, although she emphasises that this doesn’t mean it’s a parent’s fault; genetics may come into play alongside other factors, and she is currently recruiting anxiety-prone parents for a trial aiming to help them raise confident children.

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But it is about taking baby steps towards facing fears, she says, not leaping in at the deep end. “If you’ve got a child who’s scared of dogs, it’s not about taking them round to the house of your friend who owns a massive doberman. If you’ve got a child who’s very shy, encourage them if you’re out at a cafe to place their own order. Just tiny nudges to do the difficult things.” Since anxiety can be linked to perfectionism it is also helpful, she says, if parents let their children see them occasionally model “being a bit half-arsed about stuff – a bit slapdash, even if that’s quite painful”.

For teenagers approaching exams, she recommends ensuring that they’re not over-revising – “three blocks of two hours (a day) is plenty” – plus encouraging them to exercise and eat regularly. “If they’re doing revision, take them a bit of toast. Sleep is the big one – it’s becoming more and more clear that sleep has a massive impact on mental health, and if you’re not getting enough you will be so much more prone to anxiety.”

For many families, the big hurdle is recognising that anxiety can’t always be “cured” so much as managed. Michael Wilton’s 13-year-old daughter Lily was first referred to CAMHS for anxiety when she was 10, and given CBT. For a while it helped, but then she developed an eating disorder; following hospital treatment for that, she’s now back on a waiting list for the underlying anxiety. Like Harris, Wilton found it a fairly lonely experience: “It’s a difficult thing to talk about even though there are a huge number of parents going through it. It feels like it’s your fault somehow.” But his advice for parents is to be proactive, encouraging open conversations with children. “Pretending it’s not happening, or immediately leaping to what might fix it – neither of those is very helpful.”

Natasha Devon agrees. A former government tsar for teenage mental health and author of Yes You Can: Ace Your Exams Without Losing Your Mind, she has suffered from anxiety since childhood. Parents should ask “lots of open questions” rather than jumping to conclusions, she says; what looks like exam stress may not be about exams themselves, so much as unease about the next stage of adult life. But she advises against getting too sucked in when children are going round in circles, worrying about imaginary worst-case scenarios. “Essentially do a mindfulness activity where you say: ‘What’s happening right now, do you feel safe? Let’s focus on what you can control.’”

Despite her successful career, Devon’s own anxiety still lingers. “I worry that I think I’ve offended people, I’ve got really bad claustrophobia, I worry about being late, I worry about germs … at my most bad, things like just getting on a train seemed an impossible feat.”

Her message, however, is that anxiety can be managed like any other chronic illness – in her case through medication, therapy and lifestyle. “It is a bit like having diabetes; it’s something I’ve had to be vigilant about, had to adjust my lifestyle to incorporate, but it doesn’t define who I am.” It needn’t, she says, define your child either.

Some names have been changed.

In the UK, the youth suicide charity Papyrus can be contacted on 0800 068 4141 or email [email protected], and in the UK and Ireland Samaritans can be contacted on 116 123 or email [email protected] or [email protected].

In the US, the National Suicide Prevention Lifeline is on 800 273 8255. You can also text HOME to 741741 to connect with a crisis text line counsellor.

In Australia, the crisis support service Lifeline is 13 11 14.

Other international helplines can be found at befrienders.org.