A teenager dices with death every time he goes to sleep - because of a rare condition that means he stops breathing every time he nods off.
Liam Derbyshire, 17, is one of a small handful of people in the UK living with congenital central hypoventilation syndrome.
Sufferers simply forget to breathe whenever they fall asleep due to a fault in the neurological reflex that controls breathing.
The condition, which affects less than 1,500 worldwide and is also know as Ondine's Curse, means Liam has to be plugged into a life support machine and be monitored by a carer every night to keep him alive.
Doctors gave the adolescent just six weeks to live after birth, but the young man, from Gosport, South Hampshire, has defied the odds and will soon turn 18.
Liam's parents Peter and Kim Derbyshire have to monitor their son round the clock
Ther 15-year-old sleeps in his ventilator mask, which is essential to keep him alive
Parents Peter and Kim are the main part of a team providing 24-hour care for Lian using specialised GPS equipment.
Mrs Derbyshire, 56, said: 'We rely on a machine to make him breathe and without that, he wouldn't be alive. If he doesn't breathe, he dies - that's it.
'You are constantly on the alert and you worry that perhaps it's the last time you are saying good night.
'His condition is extremely rare and if we would have listened to some doctors he shouldn't be alive right now.
'He had the intent for life and so that became our job to make sure he was offered that.'
The school boy hugs his parents, who say they never get a good night's sleep out of fear
We are constantly on alert
Liam's condition means he has a very strict bedtime routine.
Mr Derbyshire usually takes charge of plugging his son into the ventilator machine and making sure everything is in order for the carer to sit and watch him sleep.
He said: 'If you ask me if I had a good night sleep the answer is no, not since the day he was born to be quite frank.
'Liam's sleeping arrangements are the electric bed which has three positions in order to give him some quality sleep.
'On the left hand side we have all of his ventilator equipment. The idea is that a ventilator supplies positive pressure so that Liam is actually forced to exhale CO2, which normally you or I would [naturally].
Liam and his two cousins smile for the camera after playing football in the park
'There is also a plate under the mattress that will sense any sort of fitting and then the only way of making sure that he is still breathing is via that type of mask.
'Besides a medical room, it's also his room and so you have got his PlayStation, the set TV and then Liam's big forte - his Lego, which is all around the room.'
Liam can lose weight extremely quickly
Liam also struggles with a bowel condition, something unrelated to the syndrome, which means he must eat substantially large portions of food throughout the day to keep his body functioning.
Mrs Derbyshire said: 'He lost a substantial part of his bowel when he was first born and now has an ileostomy bag, which he has