Why Later School Start Times Matter for Teen Health 
According To A Sleep Psychologist

Between classes, sports and other commitments, teens have a lot to manage—and early school start times can make it harder to get the requisite sleep and rest that their bodies need. Sleep is essential to teens' physical, mental and emotional health, which is why experts such as Jacqueline D. Kloss, PhD, advocate for later school start times.

Jacqueline D. Kloss, PhD

Kloss, a licensed clinical psychologist and professor in the Department of Clinical Psychology at Philadelphia College of Osteopathic Medicine (PCOM) has studied sleep health for over two decades. She advocates that high schools start at 8:30 a.m. or later, which aligns with the recommendations from the American Academy of Sleep Medicine and the American Academy of Pediatrics.

“Sleep plays a vital role in safety, health, and performance in teens,” Kloss said. “Because puberty naturally delays adolescents' internal circadian rhythm—smaking it particularly challenging for teens to drift off prior to 11 p.m.—early morning school schedules cut short the eight to ten hours of sleep their bodies need.”

When teens fall short of the recommended eight to ten hours of sleep per night, it can cause daytime impairment, including an increased drowsiness, memory and concentration difficulties, anxiety and depressed mood, as well as risk-taking behaviors. 

“The side effects of insufficient sleep among teens have also been shown to compromise immune system function, heighten the likelihood of injuries and increase automobile accidents due to drowsy driving,” said Kloss.

She goes on to say that later start times do not significantly change when teens go to bed, but instead allows them to get more sleep in the morning. “These later start times aren't meant to coddle teens, but rather align the start times to their natural sleep and circadian rhythms,” said Kloss. “Later start times can improve mood, reduce tardiness and absenteeism, improve academic performance and reduce car crashes.”

So why haven't more school districts across the tri-state area implemented later start times?

According to Kloss, the answer is not so simple and goes beyond simply moving the bell. Transportation and busing needs, the coordination of elementary- and middle-school schedules, adjustment of teachers' and families' routines, potential financial costs, community concerns, and the balancing of academic, athletic and extracurricular activities can make the transition challenging.

She experienced these obstacles firsthand when she served as a member of the Radnor Township School District’s Sleep and School Start Time Committee from 2017 to 2019. During that time, Kloss worked with the committee to help navigate school, community and family concerns as well as logistical challenges, ultimately contributing to the successful implementation of an 8:30 a.m. start time at Radnor High School.

While districts continue to weigh the logistical challenges of later start times, Kloss says families and teens don't have to wait for broader policy changes to start making sleep a priority in their home. Parents and teens can engage in healthy sleep practices, such as establishing consistent bed- and wake-time routines, getting bright light in the morning, setting electronic curfews, limiting caffeine use, balancing homework and extracurricular demands, keeping naps brief and managing stress.

“Ideally, later school start times can have a powerful public health impact for school communities, but families and teens can start improving their health today by engaging in these healthy sleep practices in their own day-to-day routines.”