Between 2007 and 2023, the share of American high school students sleeping five hours or less on school nights went from 15.8% to 23%. Nearly one in four now. That is the central number in a JAMA study that followed 120,950 students over 16 years.
The wider measure moved too. Students getting under eight hours, the amount the study treats as sufficient, rose from 68.9% to 76.8%. Three in four teens, in other words, are short of the recommended mark.
Who was counted
A team from Columbia University’s Mailman School of Public Health drew on the Youth Risk Behavior Survey, a biennial CDC survey of health behaviors among U.S. high school students. It is among the largest datasets on adolescent sleep ever assembled.
Most of the overall rise came from teens sliding out of the six-to-seven-hour range and into five hours or less. The increase in very short sleep showed up across race, gender and grade level. One difference did stand out: Black students saw a steeper rise in insufficient sleep than white students.
Not just the phone
The finding that surprised researchers most was that insufficient sleep climbed as much or more among students without behavioral risk factors, including those reporting low screen time, as among those with high screen time. NPR’s Short Wave quoted the pattern as holding “regardless of mental health symptoms, substance use, how many hours a day they’re watching TV or they’re on social media.”
Screens still matter. Blue light from phones and tablets suppresses melatonin, and social media can push bedtime later, effects documented in smaller studies. But the JAMA data suggest they cannot account for a decline this broad.
The researchers pointed instead to forces that touch every teenager. According to the CDC, most U.S. middle and high schools start before 8:30 a.m., some as early as 7:00 a.m. The American Academy of Pediatrics has recommended 8:30 a.m. or later since 2014. Most districts have not followed, citing transportation and after-school activity schedules.
Academic load has grown as well. The share of high school students taking Advanced Placement exams has roughly doubled since 2007, with more homework and more extracurriculars to match. For teens from lower-income families, part-time jobs, long commutes and shared living space cut into sleep regardless of personal choice.
What lost sleep costs
Per the American Academy of Pediatrics, teens who sleep less than seven hours score lower on standardized tests, carry lower GPAs and miss more school. Sleep-deprived teens are significantly more likely to report depression, anxiety and suicidal ideation. Sleep deprivation is also linked to higher rates of obesity, weakened immune function and more injuries among teen athletes.
The lead researchers called for “system-level changes” rather than leaving the burden to individual families. Later start times are the intervention with the most evidence behind it. California passed a law in 2022 requiring high schools to start no earlier than 8:30 a.m., and it led to measurable increases in student sleep duration. Several other states are weighing similar bills.
For families, the study’s coverage suggests steadier sleep and wake times, a cool, dark bedroom and a wind-down routine before bed. Parents worried about a teen’s sleep can also raise it with a doctor.
