Daylight saving time harms high school students’ alertness, study suggests


A new study suggests high school students suffer from sleep loss following the change to daylight saving time— a consequence that adversely affects not only their school performance but also their ability to drive, the authors argue.  

“For many years now, sleep researchers have been concerned about sleep deprivation in adolescents,” principal investigator Dr. Ana Krieger, medical director of the Weill Cornell Center for Sleep Medicine at NewYork-Presbyterian Hospital and an associate professor of clinical medicine, of medicine in clinical neurology, and of clinical genetic medicine at Weill Cornell Medical College in New York City, said in a news release. “This study unveils a potential additional factor that may further restrict their sleep in the early spring.”

Researchers at the Weill Cornell Medical College in New York City administered a sleep diary to the study participants and had them measure their nightly sleep prior to and after daylight saving time. They measured daytime sleepiness and vigilance with the Karolinska Sleepiness Scale (KSS) and the Psychomotor Vigilance Test (PVT), two standard scientific measurement tests.

The study was small, including only 35 high school students with a mean age of 16.5 years, and it was observational.

Study authors observed that participants’ nightly sleep during the week declined to seven hours and 19 minutes— a mean loss of 32 minutes per night after daylight saving time. Students’ average cumulative sleep loss on weeknights was 2 hours and 42 minutes following the change. Researchers noted that after daylight saving time, students also were less attentive, had more delayed reactions and were sleepier.

The American Academy of Sleep Medicine recommends that adolescents get more than nine hours of sleep a night. Authors of the current study said their research is the first to objectively measure high school students’ sleep and vigilance changes following daylight saving time.

The study was published in the August edition of the Journal of Clinical Sleep Medicine.