Gavin Castle's mates jokingly nicknamed him Rip Van Castle. Little did they know his constant sleepy state was caused by a potentially life-threatening condition.

Unbeknown to Gavin and his friends, he was suffering from a triple heart condition, which meant he could have dropped dead at any moment.

The problem is normally treated in babies and when Gavin was diagnosed - at 31 - he found himself being treated on a children's ward, surrounded by pictures of Winnie the Pooh and Tigger.

While the other patients snuggled up to their teddy bears, strapping Gavin read The Sun and phoned in his bets to the bookies.

Now, seven weeks after the operation, the Brighton cabbie, is relishing his new lease of life.

He said: "For the first time in my life, I feel full of energy - like a 10-year-old."

Gavin, now 32, of Sandown Road, Brighton, was famous among his friends for nodding off.

"I could sleep for up to 16 hours at a time. My mates could ring up in the middle of the day and I would be out for the count.

"I just thought I was one of those people who needed a lot of rest.

"It never occurred to me it was because there was something wrong with my heart."

Although he went to the gym regularly, he was constantly out of breath.

He said: "The time I noticed it most was when I went swimming.

"I couldn't go underwater and hold my breath for more than a few seconds. I couldn't even get to the other side of the pool. But I thought it was just me."

The first signs that something was seriously wrong came when Gavin was on holiday in Spain last year and suffered a panic attack and lost the feeling in his fingertips.

At first he put it down to too much sun and sangria. But after returning home, he had another attack and decided to seek help.

He was referred to Guy's Hospital in London and tests revealed he had been born with a hole in the heart, had narrowing arteries and a leaking valve, problems normally treated in new-born babies.

Gavin said: "They explained my problem was congenital - a child's problem which had gone unnoticed for 31 years."

Paediatric cardiologist Dr Eric Rosenthal found the hole in Gavin's heart had closed naturally over time but his arteries had narrowed to a dangerous level, preventing blood flowing into the heart properly.

The heart condition accounted for Gavin's constant lack of energy and need for sleep.

Gavin said: "When they told me I had heart trouble I broke down in tears. I really didn't want to be cut open and undergo heart surgery."

Luckily for Gavin, Dr Rosenthal decided the best course of treatment was to insert a stent - a tiny metal lattice - into his aortic artery, via a catheter inserted through his thigh.

Once in position this would hold open Gavin's collapsing arteries, allowing his blood to flow more easily and ease the pressure on his valve.

After a couple of weeks Gavin began to feel like a new man.

"For the first time in my life, I knew what it was like to have normal circulation.

"I don't exactly want to run a marathon but I do feel fitter and livelier.

"I bet at Ladbrokes up the road. Getting up that hill used to be hard work. Now I can run up."

Finding himself on the children's ward didn't phase Gavin.

He said: "I didn't mind sitting beneath Winnie the Pooh or having cartoons everywhere. And the staff were fantastic."

Gavin also unexpectedly found himself in the spotlight when the BBC came to film City Hospital at Guy's. The crew asked him if he would be in the programme.

He said: "I didn't mind at all. I thought it might help someone else who was suffering the same things."

Gavin may still have to have surgery in the future but for the time being he is fighting fit and taking fewer naps.

In the meantime, he is keen to encourage others to take care of themselves.

He said: "We spend hundreds of pounds having our cars serviced but never think of having our bodies serviced.

"I want to lead a healthier life. I feel I've been given a second chance and I want to be a better person for it.