The children of MS sufferers worry. They worry when their parent goes out for "too long" or when they themselves go out leaving the parent alone. They worry about their parent having to do too much and getting over tired, or about being on time for them so they don't have to wait too long.
They also get frustrated: at having to sometimes leave the things they are doing early, so as to be home to help their ill parent around the house, or at not feeling able to bring friends home in case their mum or dad is having a "bad" day. Or at not being able to count on their parent to be able to do the things with them they had said they would.
But, believes Sarah Bartley (12), from Dublin, whose mother Mary was diagnosed with multiple sclerosis seven years ago, there's a "closeness" children like her have with their parent that most children don't have.
Though Mary is reasonably able-bodied, moving as she does between a crutch and her wheelchair depending on how "good" or "bad" her day, fatigue is an almost constant complaint.
Sarah's brother, Conor (9), says that even on "good" days his mum can't stand for long.
"At my school hurling match last week I finished my stuff early and my mum was standing on the side watching, so I asked my teacher if I could leave early. I would like to have stayed a bit longer."
Some 6,000 people in Ireland, the majority of them women, suffer from MS. It is a progressive, degenerative condition of the central nervous system, generally diagnosed between the sufferer's 20th and 40th year. Though there is no "typical" case of MS, some typical symptoms include blurred vision, weakness, clumsiness, tingling feelings in limbs and chronic, unpredictable fatigue.
A large number of the sufferers in this country have children, many of whom have become de facto "carers" in their time off from school and play. These thousands of children carers, says the support organisation, MS Ireland, get "little or no recognition".
In an attempt to afford them some recognition MS Ireland has commissioned 10 Christmas card designs by children of people with MS.
"We don't expect to raise an enormous amount of money with them," says Máire McKeon, marketing director of the society. "The cards are more about raising awareness about the fact that there are so many people, including children, affected by MS, beyond the actual sufferer," she says.
Sarah and Conor don't regard doing things for their mum, like pushing her wheelchair when they go shopping, as hard work.
"But I hate when people park in the disabled parking bays when they aren't disabled. I think that's really selfish," says Sarah.
Conor doesn't remember his mum without MS, and, says Sarah, "he is a worrier".
"Yes, if she's out long I think: 'I hope she's OK'. I'll want to ring her," he says
Both say it's difficult when they want their mum to go, for example, to a school play they're taking part in. "Like, I can't count on her because she says she'll come and then she might be too tired," says Sarah. "I get annoyed, and then I feel guilty when I see her lying on the couch and I know she's in pain. But it's nice being able to cuddle up to her when she's in bed, and watch TV."
David O'Shea (12) lives in Pollerton, Co Carlow, with his mother Pauline, father Mick and two sisters, Fiona (15) and Amy (16 months). Though his mother was diagnosed with MS just after he was born, he says he didn't begin to notice "she couldn't do as much as my father" until he was about seven.
LIKE Sarah and Conor, he says he would worry if he had to leave his mother alone in the house. She is wheelchair-bound and a home-help is in the house while her husband is at work and Conor and Fiona are at school.
"When we come home from school, if the baby is asleep I could go out and play. If she's awake it depends on how my mother is feeling. If she needs me I'll stay in. Or other times Fiona will. Fiona does most of the cooking.
"She's a good cook," says David. His father is a truck driver and works long hours. He's not always home for dinner, he adds.
"My mother is very sociable. She's a very strong person, very loving. Every night when she's in bed I go in and put the baby in the bed with her to get her [the baby] to sleep. I sit in my mother's wheelchair and talk to her a while before I go to bed. She's great. I love her to bits, yeah. It's not hard looking after her.
"Other people have hard things to do. It's just different."
The MS Christmas cards are available from the MS Society, phone (01) 269 4599, and in shops, price €5 for five or €7.50 for 10. The MS Helpline will be open through Christmas on 1850 233 233.