That is one of the results from a recent sleep study conducted at Brown University. The study also shows teens who get the least sleep tend to earn C's and D's, while those who get the most are prone to getting A's and B's. Researchers go as far as saying one solution to helping teenagers overcome such losses in sleep is to push back the time high schools are starting in the morning. They include, encouraging your teenager to go to bed at a reasonable hour by keeping lights low in the evening and opening curtains during the day. Light that is absorbed through the eyes can help to reset the biological clock.
Kids can catch up on sleep over the weekends, but only to an extent.
On the weekends it is better to go to sleep within an hour or so of the usual bedtime, and to only sleep an hour or two later in the morning.