A study in the journal Child Development finds evidence that burning the midnight oil to cram for tests is time wasted.
The author asked 535 students from grades 9 to 12 to keep a diary of how long they studied, slept and whether they had academic problems the next day. For example: Not understanding something taught in class or doing poorly on a test or homework.
The research found that, when study time cut down on sleep time, kids performed worse in class the day after.
That doesn't mean teens should study less, but if they sacrifice sleep for study, it may hurt more than it helps.