Could you imagine going from being an active, sporty teenager to having to spend most of your day lying down?
That is what happened to Maria Shepherd whose life has, literally, been turned upside down by a chronic debilitating condition.
This time last year the 17-year-old from Hingham was loving life.
She had just sat her GCSEs at Wymondham High School, and she was school hockey captain as well as playing regularly for Dereham Hockey Club. At the end of Year 11 she received an award for the biggest contribution to sport at school.
With trips to America and Spain planned for the summer holidays she was looking forward to travelling, learning to drive and then starting her A-levels.
But just a few short months later she was diagnosed with a little-known but chronic condition called PoTS, postural tachycardia syndrome.
It affects the nervous system and causes a drop in blood supply to the heart and brain when the sufferer is upright, forcing the heart to race to compensate.
In basic terms the body is unable to adjust to gravity.
In Maria's case it causes her to faint dozens of times a day meaning she has to spend most of her time lying down and someone has to be with her 24 hours a day.
'It also means I suffer chronic pain,' she said, 'as well as brain fog, fatigue and memory loss.
'It makes it hard for me to go to school full-time so I am just doing one A-level in Spanish and go to school when I can. Wymondham High have been fantastic and really supportive as they know I would go in if I could.
'But it feels like I am living life horizontally, staring at the ceiling.'
Maria is able to walk round the house, under supervision, but when she goes out she has to rely on a wheelchair as she physically does not have the strength to carry herself any distance and could faint without warning.
Mum Corrina Willmoth, a psychologist in learning disabilities, and dad Chris Shepherd, head of maths at Norwich High School, have had to completely reorganise their lives to make sure Maria is never left on her own.
They also have another daughter Leia, 13, and have to ensure someone is at home with Maria when she needs to be taken to school or activities. 'Grandparents have been amazing,' said Mr Shepherd.
Initially Maria's symptoms baffled doctors with many trips to hospital and the GP.
'She started fainting in April last year,' said Ms Willmoth. 'Before that she would have days off school with flu-like symptoms which now we know were part of this condition.'
Maria added: 'I would crash out for two to three days and then bounce back and go back to school. I fainted in the middle of my maths GCSE and had to finish it in a separate room. I still got a B.'
But by the middle of October the fainting became worse and by December it was happening several times a day.
'Doctors initially diagnosed low blood pressure and prescribed jelly babies, more fluids and more salt in her diet,' said Ms Willmoth. 'When this didn't work we took her to hospital.'
Mr Shepherd said their approach was quite different. 'This time they were looking at the other end of the scale - meningitis, sepsis, brain haemorrhage - but nobody knew what was actually wrong.'
In January they took her to Great Ormond Street Hospital in London. It was then Ms Willmoth suggested a condition she had heard of once before.
'I have a friend whose sister had PoTS so I just said maybe they could look at that as a possiblity, just throw it into the mix, as they were looking at it from a neurology perspective and PoTS comes under the cardiology department,' she said.
Within 10 days they had the diagnosis.
Maria now has to take numerous different medications to regulate blood pressure, slow down her heart rate, and narrow the blood vessels to help return blood back to her heart.
'It also means lifestyle changes,' she said. 'I need to do more exercise and adjust my diet.
'I do try to stay positive and hope that eventually the treatment will pay off and I will get better.
'I am better than I was. For the first few months of this year I was just in bed, I was like a zombie. I was sleeping all the time, I couldn't walk, I was just out of it. Now I can do an hour in the gym on the reclining bicycle.
'But I get times when I am just fed up of being ill. My friends are learning to drive, going to parties and doing all their A-levels and I am just trying to do simple things like walking normally.'
What is PoTS?
Postural tachycardia syndrome is an abnormality of the functioning of the involuntary nervous system.
When a healthy person stands up, blood vessels contract and heart rate increases slightly to maintain blood supply to heart and brain.
In PoTS, this automatic adjustment to upright posture is not working correctly, resulting in an excessive rise in heart rate, increase of the chemical norepinephrine in the blood and altered blood flow to the brain.
Symptoms include headaches, fatigue, palpitations, sweating, nausea, fainting and dizziness.
It is five times more common in women and tends to affect people aged 15 to 50.
Abrupt onset may follow infection, pregnancy, surgery, immunisation or trauma.
Developmental PoTS sees a gradual onset around the age of 14 with symptoms peaking age 16 but 80pc resolve within a few years.
For more information visit the website.
Raising awareness
The family is keen to raise more awareness of the condition in case other sufferers are struggling to get a diagnosis.
The charity PoTS UK says its incidence in the UK is unknown but it is probably under-diagnosed due to lack of awareness in the medical community and because of its non-specific symptoms. It is often misdiagnosed as anxiety, panic attacks, or chronic fatigue syndrome.
Maria's boyfriend, Ewan Downes, is running the Run Norwich 10K on August 6 to raise money for the charity and raise awareness.
The 17-year-old, who is studying sports studies, psychology and sociology A-levels, has also organised a non-uniform day for the sixth form at Wymondham High School to raise more funds, while the school is distributing information amongst its students.
To support the fundraising go online here.
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