The study, which draws on data culled from tests taken by more than 900,000 students in 50 countries, found that the U.S. has the greatest proportion of students whose academic performance, particularly in math and science, suffers due to poor sleep, with 73% of 9 and 10-year-olds and 80% of 13 and 14-year-olds affected. Those rates are significantly higher than the international average of 47% and 57%, respectively.

The top 5 countries where poor sleep hampers learning are:

United States
New Zealand
Saudi Arabia
Kuwait
Australia