A recovering energy drink addict has called for an age limit to be imposed on the high caffeine beverages after new figures showed the extent young people rely on them.

Luke Bullard - who used to drink up to 13 cans a day - has spoken out about the health and wellbeing problems he says he suffered as a result his consumption of the drinks.

It comes as a study from the British Medical Journal showed that up to a third of children have at least one can per week.

Experts have now issued a fresh warning of the impact that drinking too much can have on young people, causing headaches and sleeping problems.

Single cans can contain more caffeine than an espresso and campaigners have said the drinks can contribute to poor behaviour and make it harder for children to concentrate in class.

Mr Bullard, now 21, said that when he was a teenager he would drink 12 or 13 cans a day.

As his reliance on the drinks worsened, he found himself in a cycle of sugar highs and crashes, struggling to sleep at night and finding it tough to concentrate at school.

Mr Bullard, from Great Yarmouth, lives with attention deficiency and hyperactivity disorder (ADHD) which he said was exacerbated by his energy drink consumption.

He said: "I used to drink three or four cans before school alone and would be so hyperactive, then by the time it got to lunch time I would have a huge sugar crash, so would just have to keep going back for more.

"It's just a constant need for that extra energy boost, but it just wasn't true energy. It became a real ongoing problem and a vicious cycle."

By the time he reached college he started to realise he had a problem and began to wean himself off the drinks - but it did not prove easy.

"I had to do it really gradually - I found that without them I would get the shakes and was incredibly irritable all the time. I really started to suffer," he added.

"I had to lose a few cans a week, which took quite some time, but now I rarely drink them at all.

"But the effects can be so harmful if they are abused, so personally I think you should have to be at least 16 to buy them. I was around 14 when I started."

Former MP Norman Lamb, now chairman of the Children and Young People's Mental Health Coalition, has called for more research to be done into the impact these drinks can have on youngsters.

Sir Norman was chairing the government's science and technology select committee in 2018 when calls were made for a ban on children buying the drinks. At the time, the committee said there was insufficient evidence to press ahead with a ban.

He said: "I think there is an argument for a ban and know that teachers do have concerns about the impact they can have on behaviour and concentration.

"However, I don't think we have clear conclusions about their impacts, but I do have concerns about them particularly among children in disadvantaged groups. There is evidence these children are more reliant on this."

Mike Smith-Clare runs the Bread Kitchen in Great Yarmouth, which offers training opportunities for young people and he said he regularly encountered teens relying heavily on the drinks.

He said: "I have seen young people become addicted to them - the youngest of whom was just 10 years old and they've become more and more of a worry.

"They become over-reliant on that instant hit of energy you get from them, but it's not sustainable and they end up looking for their next hit.

"It's almost euphoric, but there is then the big drop you get afterwards which is really damaging."

Science teacher Chris Collis, of the Norfolk branch of the NASUWT teaching union, said excessive use of the drinks had a real detrimental impact on the behaviour of children in class.

He said: "I don't necessarily think there needs to be a ban, but there has to be better focus on education about what healthy eating and drinking is.

"Parents, schools and the children themselves need to work together to better understand what they should and shouldn't be drinking. High sugar drinks do have a clear effect on how easy children's behaviour is to manage in the classroom.

Dr Louise Smith, Norfolk’s director of public health, added: “There is deep concern about the levels of harm that energy drinks can cause to children and young people: the evidence shows a worrying link between excessive consumption of these drinks and negative health outcomes.

“We would recommend that young people and their families choose a healthy lifestyle and avoid drinks high in sugar with artificially added caffeine.”

The British Soft Drinks Association says its members do not market or promote energy drinks to under-16s and that their cans carry an advisory note stating 'not recommended for children'.

A spokesman added: "The BSDA code of practice on energy drinks was introduced by and for our members in 2010 and contains a number of stringent points on responsible marketing. We remain committed to supporting the responsible sale of energy drinks."

What are the rules on energy drinks?

Currently, there is no blanket age restriction on energy drinks - although there has been a number of campaigns calling for this to come in.

However, some large retailers including supermarkets, have taken independent decisions to place limitations on purchasing the beverages.

In February last year, a petition was lodged with the government calling for an age limit of 13+ to be placed on the drinks.

But in response the government said: "At the moment there is no law that prevents under-16s from buying energy drinks, so we don't know what you'd like the UK government or parliament to do.

"Many shops and supermarkets ban people under 16 from buying energy drinks, but that is a decision for them, not the UK government or parliament."

Calls for a ban on under 18s has been backed by the Association of Directors of Public Health.

Its guidance on the subject says: "Evidence suggests the excessive consumption of energy drinks by children is linked to negative health outcomes, affecting children's physical and mental health, as well as sleep latency and duration.

"ADPH supports the age of prohibition being set at 18 and would like to see advice and guidance available to children and young people and their parents about how to improve and maintain energy levels in healthy ways."

However, health guidance on the drinks do only associate dangers with excessive use of the drinks, rather than in moderation.

What is in them?

Most energy drinks consist of high levels of sugar and caffeine.

They may also often contain extracts from the guarana plant, which is similar to caffeine, the amino acid taurine and carbohydrate in form of sugar.

The drinks are often sold in either large, 500ml cans or smaller 250ml cans.

The average 500ml can contains around 160mg of caffeine - the equivalent of three cups of black coffee and four standard cans of cola.

A Monster Energy drink, which is one of the drinks with the highest level, contains the caffeine content of four shots of Espresso and the equivalent of 13 teaspoons of sugar.

Cans of energy drinks will typically contain health warnings relating to the level of sugar and caffeine they carry, advising children and pregnant women not to consume them.