Joanne Mahon, from Haverhill, who has the rare illness sarcoidosis, is urging others to take part in medical research after a clinical trial helped transform her life.

Everyone feels tired now and again - but imagine if even something as simple as making a cup of tea left you so drained, you couldn't face the rest of the day.

It is a reality that Joanne Mahon has to face all too often.

Diagnosed with the rare auto-immune disease sarcoidosis, Mrs Mahon cannot replenish the energy she uses in day-to-day tasks - because the cells in her body to clump together and drain organs such as the lungs, skin, heart and muscles.

At its worst, Mrs Mahon will be left exhausted by a short trip to the shops and cannot even sit up straight.

She is also left with regular severe chest infections, coughs and colds due to a poor immune system.

Because chronic fatigue leaving her energy-less for days can strike at any time, making even the simplest plans to go to the supermarket or a trip to the cinema can be difficult.

While many of us might grab cup of coffee to give us a quick energy boost, Mrs Mahon says "generally there are no answers when it comes" - leaving her effectively confined to a bed or sofa.

But the 65-year-old from Haverhill has bravely fought back against the debilitating illness and chronic fatigue, still running her own luxury pet accessories brand against the odds.

And after taking part in a life-changing study helped bring about a vast improvement in her condition, she is urging others to take part in medical research.

How 'worst flu I've ever had' turned into debilitating condition

Mrs Mahon, managing director of Great Wratting-based Diamond Dogs, lived an active life up until she returned from the Crufts show one year to flu that she just couldn't shift.

"I came back with flu but it was the worst flu I've had ever had," she said.

"I was very ill for about four weeks and didn't seem to get better.

"You normally make a gradual recovery, but I couldn't regain any degree of energy. I just felt rotten."

Doctors were at first confused by what was wrong, with electrotherapy, acupuncture and light therapy not doing the trick.

It was only when she later went into hospital for a nasal operation to improve her breathing that she was told she had a devastating illness few people even know exists.

"I was definitely in shock," Mrs Mahon said of the diagnosis nine years ago.

"Your body doesn't replenish the energy it uses. You never know when it's going to happen and you never how long a period you might have each day to function.

"This in itself is very difficult to manage. Sometimes I would be drained from just having breakfast and have to go back to bed.

"I had a really active life. I travelled to the States six or seven times a year and I would go to Germany for business.

"Suddenly, I couldn't even get on a plane. I could hardly even walk to the other side of my house.

"It all makes things extremely difficult."

How did Joanne cope?

Incredibly supportive colleagues at Diamond Dogs have helped her manage her workload during her illness, while the business' move to greater online trading has also saved her needing to be on a shop floor.

However she added: "I think one of the biggest hardships of having the disease is that you're susceptible to everything else that comes at you. It's just up and down with a lot of illnesses."

She also said: "One of the most difficult parts is that it isn't a visible illness. People wouldn't look at me and think I'm disabled."

For the first seven years of her illness, Mrs Mahon saw little chance of her problems ever improving.

But as part of the clinical trial funded by the National Institute for Health Research (NIHR) and led by the Norfolk and Norwich University Hospital (NNUH), she has taken medication which has had an immediate and transformative impact on her life.

"Taking part has been the best thing I have done since my diagnosis as it's allowed me to live a more independent life," said Mrs Mahon, who added that the medication enables her to walk for 20mins.

"It's changed my life."

Another problem following her diagnosis was the "paltry" level of information available about sarcoidosis, with even many doctors lacking knowledge about the illness.

But one of the benefits of the trial is the "fantastic" staff who were "always willing to spend the time to answer all my questions".

She added: "They were so amenable to my condition, to have doctors and nurses who were so understanding was really helpful."

Being able to talk to others with sarcoidosis has also helped.

"You can feel so isolated with this condition, like you're the only person in the world struggling," Mrs Mahon said.

"Being able to listen to and share the experiences of other sarcoidosis patients was so enlightening."

The future

It would only be natural that with such a life-changing condition, Mrs Mahon might resent what has happened to her and the effects it has on her life.

However, despite its terrible symptoms, she has learned that staying positive and optimistic is perhaps the best treatment of all.

"You can't have this illness and feel like you're living a normal life, because you aren't," she said.

"You have to forgo a lot of things that you'd normally do.

"There's a high degree of resentment about being ill, but people don't have a choice. It's not something you acquire through contact with people.

"After nine years, I've learned how to manage. You have to accept that you have this disease and now your life is going to change.

"I imagine some people can be quite depressed but I'm a very optimistic person and won't let that happen to me."

Clinical research

Joanne Mahon now wants to encourage others with life-limiting illness to give clinical trials a go - not just as to help their own lives, but provide vital research data which might helps others too.

"I'm really keen to see research done, because if we don't we can't improve things and we can't improve the quality of life for patients like me and for others who suffer from this disease or other conditions," she said.

"It is a positive step forward to help people both now and in the future.

"If you're ill you have nothing to lose, you have to give yourself some hope that things can improve."

The NIHR's clinical director for the eastern region, Professor Jeremy Turner said: "We are incredibly grateful to Joanne, not only for volunteering to take part in our research but also for her ongoing support.

"We truly could not do it without the involvement of people like her.

"It is our mission to make sure every patient has the opportunity to Be Part of Research if possible, whether it be by participating in a clinical trial or by pledging to support the work being carried out to improve treatments for patients now, and in the future."

The NIHR is promoting its Be Part of Research campaign to encourage patients and the public to take part.

For more information and find out how you can Be Part of Research, visit the NIHR's website.