A devoted mother is battling a rare medical condition that puts her into a coma every time she tells her children: ‘I love you.’

Wendy Richmond, 53, slips into a ‘waking sleep’ that leaves her almost paralysed every time she becomes emotional or wants to laugh or cry.

But drugs to treat the condition are expensive and not funded by her local NHS trust, meaning she has to shut off her emotions to avoid collapsing.

Ever since her first grandchild Megan was born, Mrs Richmond has had to remain emotionally reserved.

She said: ‘I want to just sweep her up into my arms and say I love you. But I am afraid it could be dangerous for both of us.

It could trigger an episode and I could collapse on the floor, injuring Megan and myself. ‘It is quite bizarre to think I can’t tell my family I love them without falling over.’

Mrs Richmond, from Pitsmoor, Sheffield, has suffered from sleeprelated illnesses cataplexy and narcolepsy since her late teens but was diagnosed only in her 30s.

She is trying to secure NHS funding for a new drug, sodium oxybate, which doctors believe could help her.

The drug, marketed as Xyrem, has just been licensed in Britain after trials in the US but her local healthcare trust refuses to pay the £9,000 a year it would cost to treat her.

Detailed figures on sufferers are rare because most cases go unrecognised or unreported. However, experts believe there could be up to 30,000 narcoleptics in Britain.

Mrs Richmond said of her condition: ‘It has affected me all my life and has left me with several failed relationships.

‘There are many sufferers who are in the same boat and have not been diagnosed but I feel this new drug could help so many.’