LYNSEY HAYWOOD speaks to three people who tell us why these two illnesses are far more serious than most people realise.
SOPHIE ELLIS has suffered from ME since she was nine. She can't even watch TV or send a text and is fed through a tube.
She has not been downstairs in her house in Banbury, Oxon, for more than a year.
She lives with dad Mark Ellis, 52, a financial adviser, and mum Karen, 52, her full-time carer. Mark says:
When Sophie was nine she got a fairly typical virus which lasted two to three weeks.
But she never really recovered.
She suffered crippling gastric problems, heartburn and acid reflux, as well as a general lack of energy.
The GPs we saw tried to deal with the symptoms rather than the root cause.
As parents we had no knowledge of ME, so while seeing countless consultants we never thought to ask about it.
We simply thought it was something people got in the Eighties and it made you feel like you had flu.
We certainly didn't know you could treat it.
Sophie was getting worse and worse to the point where she couldn't eat and was increasingly bedbound.
Then, about two years ago, one consultant suggested ME and, after researching it ourselves, it all made sense.
Sensitive to light ... Sophie lies in a darkened room
It took up to six years to get an accurate diagnosis but sadly, by then, having pushed herself so hard for six years, Sophie's batteries were completely run down.
It felt like we'd missed our window of opportunity when we could have done something.
Now, Karen has given up her job as a shelf-stacker at Sainsbury's to be her full-time carer.
The slightest thing exhausts Sophie and because it's neurological, it affects every part of her body.
She can't watch TV or use a laptop because she's light intolerant. It makes her dizzy or ill.
She can't read more than a couple of times a day and she hasn't been downstairs for more than a year.
We can't speak to her for more than a few minutes at a time because it drains her energy.
Her room has to be dark and she needs help getting to the loo as she's too wobbly on her feet.
She can read texts but can't type herself because her brain can't co-ordinate her fingers.
Eating and chewing is now almost impossible for her, so she has a tube which feeds liquidised food through her nose, but she can drink herself.
We're trying to step up the little achievements she can manage each day – exposing her to a little more light, getting her to eat a little food herself.
But if we push her too hard she relapses badly and we're back at square one.
We can't have visitors to the house at all now because of any potential disruption. The best Karen and I can hope for in terms of our own lives is a walk and a coffee when Sophie's brother Matt, who is 29, comes round.
This makes Sophie feel terribly guilty too – ME impacts hugely on everyone.
But throughout Sophie's been bright and cheerful, always with a smile on her face.