There is nothing more wonderful than the sound of a child's laughter. But for the parents of toddler Elliot Eland it can also be distressing.
For the two-year-old suffers from a rare neurological condition which means he can't stop giggling – even when there's nothing to laugh about.
His mum, Gale, 41, said: "When we feel down, Elliot's laughter keeps us all going, you just have to look at him and his happiness takes over.
"At the end of the day when you have children you just want them to be happy, and Elliot always is.
"The only problem is if Elliot and his big brother, Alex, are playing and Alex accidently gets hurt. Alex will be crying, but Elliot just laughs and he doesn't understand why.
"That can hurt as we don't want Alex to think Elliot is happy about hurting him."
Elliot was born with Angelman's syndrome - a chromosome disorder which causes severe learning difficulties - and a permanent smile on his face.
Sufferers are often smiling or laughing, and tend to be easily excited. The condition is so rare that less than 1,000 cases have been reported in the UK.
Gale and husband Craig, 34, from Preston, Lancs only discovered Elliot's condition when he was having trouble feeding as a baby.
"It was so hard to begin with because we knew so little about it," she said.
A further symptom of Angelman's is that two-year-old Elliot appears to need only a few hours of sleep a night.
Gale said: "He goes to sleep very easily but he wakes up in the night and just lies there.
"We would guess at the moment he has about four hours sleep a night.
"We'll also need to make sure that his bedroom is safe when he's unsupervised, so a soft floor and a low bed will be really important.
"Elliot will never be able to speak, but we've done a signing course in the hope that we'll still be able to communicate with him."
Elliot's family have found comfort in the charity ASSERT, a support group to help families of those with the condition.
His family also have a fundraising society for Elliot called One Big Tickle, which can be found at www.onebigtickle.co.uk.