Delaying School Start Time By One Hour Positively Affects Adolescents' Cognitive Performance

The study, authored by Orna Tzischinsky, PhD, of Emek Yezreel College in Israel, focused on 47 eighth graders from two classes, who were divided into experimental and control groups for a two-week period. On week one, the experimental class began their school day one hour later than usual (at 8:30 a.m.), while the control class began at the regular time (7:30 a.m.). On week two, both classes began at 7:30 a.m. The subjects were asked to maintain their habitual sleep-wake pattern. Actigraphs were worn to monitor sleep-wake patterns. On the fifth day of each week, the students performed a cognitive test.

According to the results, during the first week, the experimental class woke up 51 minutes later on average than the control class, while during the second week, the experimental and the control class woke up at the same time. Bedtime and sleep efficiency remained the same during both weeks.

"The cognitive tests showed better performance with the experimental group in comparison to the control group on the first week," said Dr. Tzischinsky. "The results demonstrate that longer sleep duration positively affects cognitive functioning."

It is recommended that adolescents get nine hours of nightly sleep.