Like children everywhere, four-year-old Jess Tinsley has a structured bedtime routine. She is in the bath promptly at 6.30pm and normally falls asleep after a bedtime book by 7.15pm.
However, there the similarity with other children ends. Unfortunately for her parents, full-time mum Tanya, 25, and soldier Chris, 24, Jess has the dubious distinction of being one of Britain's youngest insomniacs.
Although she falls asleep at bedtime, often she is awake by midnight and will stay awake until morning - frequently keeping her parents awake, too.
There have been times when she has slept for only an hour or two, and once she was awake for 36 hours,' says Tanya.
'Ironically, Jess was a really good baby and slept through the night from around six months. But when she was about a year old, she started waking up and making funny little actions as if she was pretending to eat or drink, or laughing and playing with imaginary friends.
'She didn't cry - it was as if she just didn't need sleep any more. Initially, we were worried she'd hurt herself, so we'd bring her into our room, where she'd continue for hours, completely oblivious to us. Then, as she got older, she'd come in on her own.
'The doctor assured us it was nothing to worry about and said she would grow out of it - but she hasn't yet.'
Around 10 per cent of the population suffer from insomnia. It is most common in older people, partly because our sleep becomes lighter and more fragmented as we age.
'Whatever age it starts, insomnia tends to become chronic - you don't just get bouts of it, it becomes constant,' says Professor Paul Morgan, director of the Sleep Research Unit at Loughborough University.
'Only rarely will insomnia affect children - although it is, I think, more common than we recognise.
'Sometimes it is just that they have never learned sleep discipline. Babies are born with the desire to sleep, but they are not "designed" to have regular sleeping patterns. If they slept for long periods like adults, they'd end up under-nourished. They need regular feeding.
'Over time, they are trained to sleep for longer periods.
Most parents manage to help their child develop sleeping patterns, but sometimes this goes awry and a child will either sleep too much some nights and cat nap the rest of the time, or will nap through the day, leading to a repeated lack of refreshing sleep.'
Jess has seen dozens of doctors, who have all been baffled by the cause of her insomnia.
Then in March this year - over two years after her problems began - doctors discovered the cause. Jess spent the night in a children's sleep clinic, where tests revealed that she wakes up to act out her dreams - usually an almost exact version of what she has done during the day.
This ability to conjure up accurate mental images is known as eidetic imagery. It generally only affects children, as they tend to grow out of it.
But what started as a couple of one-offs has become a habit for Jessica. Because this play-acting is so enjoyable, the experience has become addictive - so much so that she subconsciously cuts short her night's sleep to enjoy hours of it.
'Older children who do this describe it as seeming like they are part of a TV programme or a play,' says Dr Paul Gringas, a sleep expert from the Evelina Children's Hospital in London where Jess was assessed.
'And while it can look strange to others, it is relaxing for Jess. From monitoring her brain during these episodes, we can see that Jess has alpha brain waves during them. These are what you get when you are zoning out - and what adults get when they meditate.
'She will be aware of what she is doing, but will be in her own little world as she does it.'
despite the pleasure it gives Jess during the night, it is ruining the family's days.
'Some days she is very tired and weepy - but we try not to let her sleep in the day in the hope that it will encourage her to sleep through the night,' says Tanya.
'We have never done things like mother and toddler groups together, because both she and I have been too tired.'
The Tinsleys now know it is a cycle they must break, as a persistent lack of sleep is not only horrific for them, but can also hamper a child's development - and they fear she will struggle when she starts school.
'Sleep does not just refresh - a full night's sleep is vital for brain development,' says Dr Gringas.
'This is when some connections in the brain are kept, while others are lost. Being sleep-deprived means you miss out on this fundamental part of development.'
Professor Morgan adds: 'It is an acknowledged cause of underachievement. It's corrosive for children or adults - it has a big impact on mood and can lead to depression in the long-term.'
Earlier this year, Jess was referred to the Evelina Children's Hospital in London. To assess just how much sleep she was getting, Jess had to wear a watch-like device night and day for a month. The watch contained a movement monitor; no or very limited movement proved she was in deep sleep.
A child of Jess's age needs between ten and 12 hours sleep a night. She was having, on average, half that amount.
But nobody knew if Jess was fully awake or asleep during her night-time play episodes, so she was monitored for a night in hospital. Electrodes attached to her head checked brain waves to determine which phase of sleep she was in, and cameras recorded her movements.
'After a few hours, the video and monitors showed her sitting up and doing her little movements,' said Tanya. 'She also shrieked from time to time - which she normally does not do at home.
'The print-outs showed, rather surprisingly, that she was wide awake during these periods. As she was oblivious to everyone, we had assumed she was almost sleepwalking.'
Jess was referred to a psychologist to help the family break her habit. Unfortunately, they cannot stop the play-acting - that is something doctors still believe Jess will grow out of - so what was important was to break the association Jess had of her parents' room being the fun place to be at night.
'The psychologist suggested that rather than having her bedtime story in the sitting room, she would have it in bed, so that she knew that was where she had to stay,' says Tanya.
'She also told us that if Jess got up, we had to put her back into bed without talking to her or making any eye contact.
'She might still wake up and play-act in her own room, but by knowing she can't come into ours, her sub-conscious would keep her asleep for longer.'
The new techniques paid off after three nights.
Tanya says: 'Jess sleeps through about three or four nights a week.
'She has also started at preschool nursery and teachers haven't reported any problems. They say she is a very bright girl.'
Jess is still going back to the hospital for check-ups once a year.
Happily, the couple's second child, Ryan, who was born in September 2007, is a good sleeper.
Tanya adds: 'It was reassuring for me, as I did start to question if Jess's problem was down to me. But now I know Jess's sleeping patterns are just a peculiarity.'
However, there the similarity with other children ends. Unfortunately for her parents, full-time mum Tanya, 25, and soldier Chris, 24, Jess has the dubious distinction of being one of Britain's youngest insomniacs.
Although she falls asleep at bedtime, often she is awake by midnight and will stay awake until morning - frequently keeping her parents awake, too.
Breaking bad habits: JessTinsley with her mother Tanya
There have been times when she has slept for only an hour or two, and once she was awake for 36 hours,' says Tanya.
'Ironically, Jess was a really good baby and slept through the night from around six months. But when she was about a year old, she started waking up and making funny little actions as if she was pretending to eat or drink, or laughing and playing with imaginary friends.
'She didn't cry - it was as if she just didn't need sleep any more. Initially, we were worried she'd hurt herself, so we'd bring her into our room, where she'd continue for hours, completely oblivious to us. Then, as she got older, she'd come in on her own.
'The doctor assured us it was nothing to worry about and said she would grow out of it - but she hasn't yet.'
Around 10 per cent of the population suffer from insomnia. It is most common in older people, partly because our sleep becomes lighter and more fragmented as we age.
'Whatever age it starts, insomnia tends to become chronic - you don't just get bouts of it, it becomes constant,' says Professor Paul Morgan, director of the Sleep Research Unit at Loughborough University.
'Only rarely will insomnia affect children - although it is, I think, more common than we recognise.
'Sometimes it is just that they have never learned sleep discipline. Babies are born with the desire to sleep, but they are not "designed" to have regular sleeping patterns. If they slept for long periods like adults, they'd end up under-nourished. They need regular feeding.
'Over time, they are trained to sleep for longer periods.
Reassuring: Tanya and Jess with husband Chris and son Ryan, who is a good sleeper
Most parents manage to help their child develop sleeping patterns, but sometimes this goes awry and a child will either sleep too much some nights and cat nap the rest of the time, or will nap through the day, leading to a repeated lack of refreshing sleep.'
Jess has seen dozens of doctors, who have all been baffled by the cause of her insomnia.
Then in March this year - over two years after her problems began - doctors discovered the cause. Jess spent the night in a children's sleep clinic, where tests revealed that she wakes up to act out her dreams - usually an almost exact version of what she has done during the day.
This ability to conjure up accurate mental images is known as eidetic imagery. It generally only affects children, as they tend to grow out of it.
But what started as a couple of one-offs has become a habit for Jessica. Because this play-acting is so enjoyable, the experience has become addictive - so much so that she subconsciously cuts short her night's sleep to enjoy hours of it.
'Older children who do this describe it as seeming like they are part of a TV programme or a play,' says Dr Paul Gringas, a sleep expert from the Evelina Children's Hospital in London where Jess was assessed.
'And while it can look strange to others, it is relaxing for Jess. From monitoring her brain during these episodes, we can see that Jess has alpha brain waves during them. These are what you get when you are zoning out - and what adults get when they meditate.
'She will be aware of what she is doing, but will be in her own little world as she does it.'
despite the pleasure it gives Jess during the night, it is ruining the family's days.
'Some days she is very tired and weepy - but we try not to let her sleep in the day in the hope that it will encourage her to sleep through the night,' says Tanya.
'We have never done things like mother and toddler groups together, because both she and I have been too tired.'
The Tinsleys now know it is a cycle they must break, as a persistent lack of sleep is not only horrific for them, but can also hamper a child's development - and they fear she will struggle when she starts school.
'Sleep does not just refresh - a full night's sleep is vital for brain development,' says Dr Gringas.
'This is when some connections in the brain are kept, while others are lost. Being sleep-deprived means you miss out on this fundamental part of development.'
Professor Morgan adds: 'It is an acknowledged cause of underachievement. It's corrosive for children or adults - it has a big impact on mood and can lead to depression in the long-term.'
Earlier this year, Jess was referred to the Evelina Children's Hospital in London. To assess just how much sleep she was getting, Jess had to wear a watch-like device night and day for a month. The watch contained a movement monitor; no or very limited movement proved she was in deep sleep.
A child of Jess's age needs between ten and 12 hours sleep a night. She was having, on average, half that amount.
But nobody knew if Jess was fully awake or asleep during her night-time play episodes, so she was monitored for a night in hospital. Electrodes attached to her head checked brain waves to determine which phase of sleep she was in, and cameras recorded her movements.
'After a few hours, the video and monitors showed her sitting up and doing her little movements,' said Tanya. 'She also shrieked from time to time - which she normally does not do at home.
'The print-outs showed, rather surprisingly, that she was wide awake during these periods. As she was oblivious to everyone, we had assumed she was almost sleepwalking.'
Jess was referred to a psychologist to help the family break her habit. Unfortunately, they cannot stop the play-acting - that is something doctors still believe Jess will grow out of - so what was important was to break the association Jess had of her parents' room being the fun place to be at night.
'The psychologist suggested that rather than having her bedtime story in the sitting room, she would have it in bed, so that she knew that was where she had to stay,' says Tanya.
'She also told us that if Jess got up, we had to put her back into bed without talking to her or making any eye contact.
'She might still wake up and play-act in her own room, but by knowing she can't come into ours, her sub-conscious would keep her asleep for longer.'
The new techniques paid off after three nights.
Tanya says: 'Jess sleeps through about three or four nights a week.
'She has also started at preschool nursery and teachers haven't reported any problems. They say she is a very bright girl.'
Jess is still going back to the hospital for check-ups once a year.
Happily, the couple's second child, Ryan, who was born in September 2007, is a good sleeper.
Tanya adds: 'It was reassuring for me, as I did start to question if Jess's problem was down to me. But now I know Jess's sleeping patterns are just a peculiarity.'