More than a third of primary school children are failing to get sufficient sleep, according to research to be presented at the British Sleep Society conference tomorrow (October 12th).
The study has linked poor sleep with difficulties in paying attention in class, keeping up with school work, forgetfulness and absenteeism.
The NHS recommendation is that children of that age should get ten 10 hours sleep per night.
The study discovered that out of 1,100 children aged six to 11, 36 per cent were getting eight hours or less sleep on a weekday night.
There was a sizeable minority - one in seven or 15.2 per cent - who were getting seven hours or less a night.
The researchers found links between poor sleep and children having access to mobile phones or computer devices in their bedroom. They say parents should consider removing technology from their children's bedrooms.
The study, conducted by the University of Leeds and commissioned by the bed manufacturer Silentnight, was designed to provide an insight into the sleeping patterns of young children in the UK, an area that has previously received little attention from scientists.
Lead researcher, psychologist Dr Anna Weighall from the School of Psychology, set out to assess the use of technology such as mobile phones, tablets and computers in the run up to bedtime, the availability of technology in the bedroom, and what impact that was having on children's sleep.
The researchers identified that children who had access to technology in their bedroom were more likely to experience a shorter night's sleep. One in 3 parents (34%) reported that their children use a smart phone, tablet, or other electronic device in the hour before bedtime, and many children sleep with ready access to electronic devices.
Dr Weighall said: "There is a clear relationship between technology use and shorter sleep duration. We asked parents if their child had technology in the bedroom, and having the technology in the bedroom is associated with much shorter sleep durations in children.
"Where parents are able to encourage their children not to have technology in the bedroom at all, the sleep outcomes are much better."
It's not known what might be causing that effect but Dr Weighall has a number of theories. She said that scientists know that the light from a screen excites the brain, making it harder for those children who are using their phone in the run up to bedtime or in bed, to switch off. Unable to sleep, they could also get themselves locked in a vicious cycle of further technology use.
Dr Weighall added: "It is conceivable that if a child can't sleep, they are more likely to pick up their phone.
"When your child enjoys being on technology, it is quite difficult to have that row at bedtime to say 'you are not taking it into the bedroom' - my intuition it is simply that if you don't have it in the bedroom you are going to have a longer gap between stopping using the technology and actually going to sleep."
The parents or carers of 1,100 children aged from six to 11 were asked to fill out a detailed questionnaire about their own and their children's sleep. The study was observational and therefore identified associations between factors rather than direct causal links.
Just under a third of children (29 per cent) were regularly telling their parents that worrying about school work was keeping them awake. A smaller group - around one in six - (16 per cent) told their parents they found it difficult to sleep because of concerns about bullying or friendship.
The survey also found that in some families poor sleep seemed to be a problem faced by children and adults alike, with 40 per cent of parents saying they did not get enough sleep. In fact a quarter of parents said they slept for five hours or less a night. Among the parents, 16.5 per cent said they were dissatisfied with how long their children slept.
Dr Nerina Ramlakhan, Silentnight's sleep expert, said: "Sadly I'm not surprised by the impact a lack of sleep is having on the nation's children. It is so important for parents to recognise how essential good quality restorative sleep is for children.
"Ten hours might seem a lot but children's brains are constantly growing and developing, particularly at primary school age, and having time to rest and recover after a busy day at school is vital.
"It's interesting to see how much parents' sleep affects children's and I think this boils down to establishing a good routine for everyone in the household. This means the whole family limiting technology around bedtime and allowing time to wind down before going to sleep.
"Concentration and the ability to learn can be severely affected by lack of sleep. By establishing a regular sleep routine like this the whole family will sleep better, perform better at school and work, and be happier and healthier as a result."