For many years now, there have been discussions about how high school start times are too early for teenagers and that this continuous lack of sleep affects both their health and academic performance. Last year, schools in Seattle shifted their start time by 55 minutes, allowing researchers to study the effects of more sleep on students.
As reported in Science Advances, the delayed start time meant students got more sleep and achieved better grades. What's more, they were less likely to be absent from school, but only if they attended a more economically disadvantaged school.
The team followed sophomore students (around the age of 15) in two schools, Roosevelt High and Franklin High, and monitored them for two weeks before and after the change in start time. The difference was quite stark.
The researchers saw a median increase in sleep duration of 34 minutes, with students sleeping an average of 7 hours and 24 minutes compared to the 6 hours and 50 minutes that they got before. This is still far from the recommended 8 to 10 hours that teenagers should sleep but it is certainly a good improvement. And it led to students being much more alert during class.
“We decided to do a study on the sleep of the students in two high schools," said co-author Horacio de la Iglesia in a video (below) discussing the study. "This study used watches that measure activity which can give a very accurate measurement of when students are sleeping and how the sleep changed with this change in schedule.
"What we saw is that the students were waking up about 45 minutes later but they weren’t really going to bed much later... Adding these 35 minutes of sleep is really a significant increase.”
The extra sleep clearly has many benefits. In addition to their attention spans, the students' grades also improved. The team recorded a median increase of 4.5 percent in both schools. Attendance was also better for the students at Franklin High School, in terms of both late arrivals and absenteeism. Franklin High is an economically disadvantaged school and the researchers argue that this change could help reduce the learning gap between low and high socioeconomic groups.
Many teenagers are chronically sleep-deprived. Their circadian rhythm naturally makes them sleepy later in the evening compared to adults so both experts and organizations like the American Academy of Pediatrics have argued that school start times should be delayed. This study provides more quantitative evidence of the benefits that this can have.