Kids who get enough sleep may be less likely to show signs of ADHD or other behavioral issues, the BBC reports. A Finnish study of 280 healthy kids aged 7 and 8 found that those who slept less than 8 hours were most hyperactive. Researchers say a third of US kids likely don’t get enough rest—and instead of appearing tired, those children may be acting up.
The study leaders surveyed parents on their children’s sleep habits and also had the children wear actigraphs, which showed their actual rest time. Parents tended to overestimate the amount their kids had slept. Still, "sleep needs differ between individuals," said a researcher, who noted that while not every person requires the traditional 8 hours, even an extra 30 minutes of rest helps brain function.