The patient was a 4.5-year-old blind and mentally retarded child with cerebral palsy. The doctor was asked to see him because he seemed distressed. But when the doctor examined him, she found the pressing problem for the severely brain damaged boy had little to do with his physical or mental disabilities per se. And neither was he in pain. Rather, it was sleep deprivation, which caused the child to be irritable. 'You may think a mentally handicapped child knows no smile,' said Virginia Wong, professor of paediatrics and head of child neurology at the University of Hong Kong. 'You are wrong.' 'This child was in distress because he had a sleeping problem. Once that was treated, he became a happy child. He has been smiling a great deal recently, you would be amazed.' Sleep disturbances in children are among the leading concerns for parents. Research shows that bed time struggling and night awakenings affect about 20 per cent of the general paediatric population. Although their problems are generally transient and mild, in most cases they improve when parents are properly advised. In contrast, 80 per cent of mentally and physically handicapped children suffer from sleep disorders. Overseas research shows that children who are blind, mentally retarded, or suffer Down's syndrome, autism or head injuries are unable to fall asleep for several hours. They may wake up several times a night, or not sleep at all at night. Their problems - often chronic - are difficult to treat. Doctors are often reluctant to prescribe sedatives, said Professor Wong, because the drugs could be addictive, and children may become tolerant of them. The best solution is often melatonin - the miracle hormone that the body produces naturally to give us the cue to wind down and nod off. Professor Wong said that when the boy's mother was told of the possible benefit of melatonin, she bought some over the counter. The effect was dramatic. Once the critically blind child did not know when to sleep, and was often lethargic during the day. But now 'when he wakes up in the morning, he is just happy,' said the mother. 'Sleep matters. He is mentally retarded but he still needs to have a day and a night,' she said. 'He needs to be alert enough for his exercise every day.' 'When he has had a good night's sleep, he is much more open to learning. He is starting school in September. We try to get him to develop the best he can, so he needs to be able to sleep at night.' Sleep disorders in physically and mentally disabled children are often overlooked, said Professor Wong. 'But if you come to think of it, there are often only two problems that bother parents: feeding and sleeping. If their children eat well and sleep well, the parents will be hap- py. 'If not, night after night, the entire family's sleep is interrupted because their disabled child can't sleep. Sleep deprivation may cause the parents to become easily irritated and lose patience with the child. As a result, the child may suffer.' Disorders such as blindness, cerebral palsy or autism, diminish a patient's ability to perceive and interpret a multitude of cues for synchronising their sleep with their environment. Researchers believe they have difficulties adjusting to the light-dark cycles and may not be able to use 'behavioural, cultural, nutritional cues, temperature variations and knowledge to clock time.' A major study carried out by a group of Vancouver doctors also shows the dramatic effect of melatonin on disabled children. The review shows that in 82 per cent of the cases, complete or partial success was reported. About half of the children's sleep patterns improved with the first melatonin dose. According to researchers James Jan and Maureen O'Donnell, 'the results were so dramatic that the care-givers called it a miracle, especially when their children's severe chronic sleep disorders were resistant to all forms of management.' In others, the response, although gradual, was so positive that several months was usually sufficient for the sleep pattern to become normal. There have been no reported side effects since the use of melatonin began in 1991. And none of the children have developed a tolerance to the hormone. The researchers reported that as the children began to sleep more normally, the parents saw them as 'less irritable, calmer, happier, more playful, content and affectionate, with fewer temper tantrums. 'The children were able to socialise better and were gentler with their siblings and pets. 'They became more attentive, and their cognitive abilities and mobility improved.' About 140 children have been treated with melatonin since late 1991 and it appears that better sleep did result in a better mood. The study conducted by the Children's Hospital of British Columbia reviewed the effects on the first 100 patients, aged from three months to 21 years. More than half the subjects were visually impaired and 85 per cent of them had multiple neurodevelopmental disabilities, such as mental retardation, cerebral palsy, and epilepsy, autism, brain tumours. Those who were not multi-disabled were diagnosed with attention deficit hyperactive disorder, anxiety, bowel disorders and nocturnal seizures. Research also indicates that melatonin may have an additional use for handicapped children. Parents almost consistently commented that their children had fewer infections and were generally healthier. Increased appetite and growth rate were also noted. Although more research is required in these and other aspects, studies have shown melatonin as having an anti-convulsant action, indicating the drug may be beneficial for children with epilepsy. The researchers conclude that 'the improvement of sleep in our subjects meant major benefits for the entire family . . . The parents and sibling were also able to sleep, resulting in improved quality of life and health, emotional and economic benefits.' Professor Wong said, however, that more research needed to be done locally. The Vancouver study relied heavily on parents charting their children's sleep patterns before and after the melatonin treatment. Professor Wong has put in a request for funds to study the number of hours handicapped children sleep before and after melatonin treatment. The idea is to carry the Vancouver study forward and prove the absolute benefits of melatonin on these children. But at the moment, 'we don't have money to buy melatonin even for a pilot study,' said Professor Wong. 'Our hospital hasn't had melatonin in stock.'