When Linda Garland visits Lorraine Smith, Mrs Smith goes up to the bedroom, closes the door and goes to bed. It is the only time during the week that, safe in the knowledge that her two-year-old son, Sam, is being well looked after, Mrs Smith can enjoy undisturbed sleep.

For Sam Smith is not the sort of child you could leave with an ordinary baby-sitter, an older child or even a grandparent. He was born prematurely and weighed just 1lb 9oz, with the result that he has apnoea - difficulty in breathing, caused by permanent damage to his lungs. Every so often he stops breathing and turns blue. 'If he goes blue, we have to resuscitate him and phone for an ambulance,' explains Mrs Smith. Sam also has oxygen equipment at home to help him to breathe. 'I can't leave him for a second. He has to go everywhere I go.'

Mrs Smith, from Brighton, lives on her own with her four other children, aged from 7 to 13. Linda Garland, a paediatric nurse in the casualty department of Brighton's Royal Alexandra Hospital for Sick Children, offers her respite from her constant supervision of Sam.

Ms Garland belongs to a singular baby-sitting service for children with special needs called Specialised Sitting Service at Home (SSSH). She normally arrives in the evenings and sits in an armchair by Sam's cot for between 9 and 12 hours overnight, allowing Mrs Smith to wash her hair, have a bath or just sleep.

'When Sam is going through a bad patch, she literally stays up all night and watches him,' explains Ms Garland. 'I go there and stay the night so she can sleep and not worry. It takes the pressure off.

'Sam has an apnoea alarm which fits on to the stomach and picks up the movement of breathing and would go off if he stopped. But you can't rely on them 100 per cent. Once kids stop breathing they judder, so the alarm would still pick up movement - and Sam is always pulling his off.'

The baby-sitting service was set up 18 months ago by Rosie Cole, a paediatric nurse at the Royal Alexandra Hospital, in response to a government initiative under which organisations were invited to submit their ideas to the Department of Health for schemes to help children with life-threatening conditions. Ms Cole's project was one of 30 given approval. She has a government grant of pounds 10,000 a year for three years to cover the training and payment of the sitters. The project is part of her work as a paediatric liaison officer.

She has 18 sitters, from a variety of backgrounds. Half are nurses, the other half clerical workers or medical secretaries. For insurance purposes they all work for the two local health authorities, the South Downs Health NHS Trust or Brighton Health Care. They are paid pounds 8.50 an hour before tax, but to the families the service is free.

Each sitter always sits for the same child, for continuity. If the sitters have no relevant qualifications - which usually means not being trained nurses - Ms Cole teaches them how to insert naso-gastric tubes, give anti-convulsants, pessaries and, if necessary, carry out basic physiotherapy or occupational therapy. But the sitters are employed as baby-sitters rather than professionals and are expected to call for medical help for any problems they cannot deal with. 'If you can train a mother to look after her sick child, you can train someone else to look after that sick child as well,' says Ms Cole.

The 20 families on SSSH's books, who were referred through local hospitals or GPs, are assessed individually and allotted a number of hours a month, varying from 10 to 30. 'One family has someone overnight twice a week, others just want an evening out,' explains Ms Cole.

The children themselves suffer from a variety of complaints, including epilepsy, cerebral palsy, cystic fibrosis and brittle diabetes; the last means that blood sugar levels can suddenly change, pushing the child into a hypoglycaemic fit. The sitters also help with premature babies, such as Sam, and those with congenital heart disease. Some children have been sent home to die; others are not expected to survive long; others have serious chronic illnesses. 'We felt it would be better for these children to be in their home setting if their parents could be given the support they need,' says Ms Cole.

Tony and Tina Stenberg's son, Jonthon, has cerebral palsy. He has little mobility but is as mentally energetic as any three-year-old, wide awake by 6am. Both the Stenbergs work full-time and Jonthon is placed in a local company creche. He rarely goes to sleep before 10.30pm, and often Mrs Stenberg goes to bed before him.

They have used the service for six months and have provision for 20 hours a month, which they use at weekends, enabling them to go out for a meal, together or with friends. 'It's a long day with Jonthon, and SSSH allows us to have a break away from him,' says Mr Stenberg. 'It gives us time to talk to each other - we don't usually have time to communicate during the evenings.'

To many of the families, the service is a lifeline, the difference between going out occasionally and staying at home 24 hours a day, seven days a week. It allows them time with their other children, who often feel left out when there is a child with special needs in the family.

'Having a disabled child places enormous stress on the family, especially when they don't get much sleep and don't have the time to talk with each other,' says Mrs Cole. 'I've seen one family where the parents were going to split up because they had no time for each other at all.' The couple used the sitting service to visit a marriage guidance counsellor regularly, she says. 'They are now back together again and much, much happier.'

Ms Cole is preparing for the time when her grant runs out. She is confident that part of the money for it to continue will be provided by the South Downs Health Trust, but not all. 'If we can't raise the full amount, the service will fold, which is a shame. For what we can offer, it's not expensive. It costs pounds 240 to keep a disabled child in hospital overnight when the mother can't cope any longer, but just pounds 80 for a sitter.'

SSSH, Royal Alexandra Hospital for Sick Children, Dyke Road, Brighton, BN1 3JN. Tel: 0273 328145.

(Photograph omitted)