1. Benefits of REM sleep
Scientists know that children spend much more time than adults in rapid eye movement (REM) sleep, which is the dream stage of the sleep cycle. Infants spend about eight hours in REM sleep; young adults spend about 90 minutes in REM sleep. REM sleep is a crucial time for brain activity. The brain is at least as active during the dream cycle as it is when we are awake. Scientists assume all this activity is related to neural plasticity -- the growth and change of brain cells -- and believe that REM sleep provides the opportunity for this growth and change.
2. Sleep helps a child's memory
In an American study of kids aged 10 to 14, researchers limited their sleep to just five hours. The next day, both their abstract thinking and their creativity (as measured with standardized tests) had decreased temporarily. One study of nine- to 12-year-old Israeli children, released in 2003, showed that reducing children's sleep by a single hour negatively affected the amount they could remember and their reaction time on standardized tests, says Avi Sadeh, author of the study and an associate professor in the department of psychology at Tel Aviv University.
3. Lack of sleep causes daytime exhaustion
Sleep deprivation in children begins during the school years, says Sadeh. His study of school-age Israeli children (from grades 2, 4 and 6) in 200 found that Grade 6 students slept significantly fewer hours than younger children in the study and reported much higher rates of daytime sleepiness. "The sleep behaviour of older children may not be in accordance with their physiological needs," he concludes, and he warns that these children are at risk of chronic sleep deprivation.
4. Higher risk of injury
An Italian study of emergency-room visits by young boys in 2001 showed a connection between injury risk and less than 10 hours' sleep.
5. Lack of sleep can cause attention problems
Kids who don't get enough sleep can also show signs of hyperactivity disorder, and more activity is one way that kids keep themselves awake. "If you have a child who has an attention problem, impulsivity, hyperactivity or any other behavioural problem, you have to examine the sleep issue," says Dr. Judith Owens, director of the pediatric sleep disorders clinic at Hasbro Children's Hospital in Providence, R.I. Although all hyperactivity isn't caused by insufficient sleep, more sleep is the first thing suggested by doctors to treat this condition.
6. Childhood obesity is linked to sleep apnea
American figures say that 30 per cent of children are clinically obese. This is worrisome because obesity can cause sleep apnea, a condition that causes people to temporarily stop breathing. The cycle repeats itself over and over again during the night, resulting in fragmented, poor-quality sleep.
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