Kids who get enough sleep are more well-behaved than those who are sleep-deprived, according to a small new study to be published in the journal Pediatrics.
Researchers from McGill University found that elementary-schoolers who got less sleep were more likely to lose emotional control in the classroom -- they cried and got angry more often and also seemed more impulsive -- than their well-rested counterparts, CNN reported.
"Nobody became a genius, and nobody became crazy," study researcher Reut Gruber, a psychologist at McGill, told TIME, "but the findings show that in children small changes can make a big difference, and that is why this is meaningful."
The study included 34 children (33 finished the study) between ages 7 and 11, who all got about nine hours of sleep per night at the start of the study. For five nights, half of them had their bedtimes adjusted so that they slept one fewer hour of sleep a night, while the other half had their bedtimes adjusted so they had one more hour of sleep a night, HealthDay News reported.
Overall, children whose bedtimes were moved to accommodate for more sleep got 27 more minutes of sleep per night than they normally would have, while those whose bedtimes were moved to accommodate for less sleep got 54 fewer minutes per night than they normally would have, CNN reported. These measurements were recorded by actinographs worn by the children as they slept.
The researchers had the children's teachers -- who were unaware of which kids got more sleep and which kids got less sleep -- rate their behavior during that week to find how sleep affected their behavior and coping skills throughout the day.
According to the National Sleep Foundation, school-aged kids ages 5 to 12 need 10 to 11 hours of sleep. Preschoolers need 11 to 13 hours of sleep a night, and toddlers need about 12 to 14 hours of sleep every 24 hours.
