sleep duration students

Teens sleep longer, are more alert for homework when school starts later

Middle and high schoolers felt less sleepy and more engaged in academics

June 7, 2019

Science Daily/American Academy of Sleep Medicine

Preliminary findings from a new study of middle school and high school students suggest that they got more sleep and were less likely to feel too sleepy to do homework after their district changed to later school start times.

 

In fall 2017, the Cherry Creek School District in Greenwood Village, Colorado, delayed school start times for middle school by 50 minutes (changing from 8 a.m. to 8:50 a.m.) and for high school by 70 minutes (changing from 7:10 a.m. to 8:20 a.m.). Results show that one year after the change, self-reported sleep on school nights was 31 minutes longer among middle school students and 48 minutes longer among high school students.

 

"Biological changes in the circadian rhythm, or internal clock, during puberty prevents teens from falling asleep early enough to get sufficient sleep when faced with early school start times," said principal investigator Lisa J. Meltzer, Ph.D., an associate professor of pediatrics at National Jewish Health in Denver, Colorado. "This study provides additional support that delaying middle and high school start times results in increased sleep duration for adolescents due to later wake times."

 

The American Academy of Sleep Medicine recommends that middle schools and high schools should start at 8:30 a.m. or later to support teen health, alertness and safety. However, a previous data analysis by the Centers for Disease Control and Prevention found that only 14% of high schools and 19% of middle schools started at 8:30 a.m. or later.

 

The study involved more than 15,000 students in grades 6-11 who completed online surveys during school hours before the start time change in spring 2017 (n=15,700) and after the start time change in spring 2018 (n=18,607). The survey included questions asking about weekday and weekend bedtime, wake time and total sleep time; sleepiness during homework; and academic engagement.

 

The study also found that the percentage of students who reported feeling too sleepy to do their homework declined after the school start time delay from 46% to 35% among middle school students and from 71% to 56% among high school students. Scores on a measure of academic engagement were significantly higher after the start time change for both middle school and high school students.

 

"The study findings are important because getting enough sleep is critical for adolescent development, physical health, mood, and academic success," said Meltzer.

 

CCSD Superintendent Dr. Scott Siegfried said that the study supports firsthand feedback he's received from students across the 108-square-mile district.

 

"I don't know how many of our high school students have come up to me and said, 'This has changed my life for the better.' They've told me they're getting up to an hour of additional sleep before school starts," Siegfried said. "That extra sleep makes a real difference in terms of health and wellness. The input from our students and the numbers from this landmark study point to the same conclusion: The change in our start times has been a positive step and benefited our students' everyday routines."

 

The research abstract was published recently in an online supplement of the journal Sleep and will be presented Wednesday, June 12, in San Antonio at SLEEP 2019, the 33rd annual meeting of the Associated Professional Sleep Societies LLC (APSS), which is a joint venture of the American Academy of Sleep Medicine and the Sleep Research Society.

 

Meltzer is also the senior author of another abstract from this study, "Impact of Changing School Start Times on Teachers/Staff," which found significant benefits of later school start times for middle and high school teachers and school-based staff. They reported increased sleep duration due to later wake times, as well as improvements in daytime functioning.

 

"This is the first large study to examine the impact of healthy school start times on teachers and staff," said Meltzer. "It is important to consider that this policy change, critical for the health and well-being of students, also impacts other members of the school community."

https://www.sciencedaily.com/releases/2019/06/190607113825.htm

Teens get more sleep with later school start time

December 12, 2018

Science Daily/University of Washington

In 2016, Seattle Public Schools pushed back start times for its 18 high schools by 55 minutes. Researchers have now announced that, as a result, teens at two Seattle high schools got more sleep on school nights -- a median increase of 34 minutes of sleep each night -- and showed improved attendance and grades.

 

When Seattle Public Schools announced that it would reorganize school start times across the district for the fall of 2016, the massive undertaking took more than a year to deploy. Elementary schools started earlier, while most middle and all of the district's 18 high schools shifted their opening bell almost an hour later -- from 7:50 a.m. to 8:45 a.m. Parents had mixed reactions. Extracurricular activity schedules changed. School buses were redeployed.

 

And as hoped, teenagers used the extra time to sleep in.

 

In a paper published Dec. 12 in the journal Science Advances, researchers at the University of Washington and the Salk Institute for Biological Studies announced that teens at two Seattle high schools got more sleep on school nights after start times were pushed later -- a median increase of 34 minutes of sleep each night. This boosted the total amount of sleep on school nights for students from a median of six hours and 50 minutes, under the earlier start time, to seven hours and 24 minutes under the later start time.

 

"This study shows a significant improvement in the sleep duration of students -- all by delaying school start times so that they're more in line with the natural wake-up times of adolescents," said senior and corresponding author Horacio de la Iglesia, a UW professor of biology.

 

The study collected light and activity data from subjects using wrist activity monitors -- rather than relying solely on self-reported sleep patterns from subjects, as is often done in sleep studies -- to show that a later school start time benefits adolescents by letting them sleep longer each night. The study also revealed that, after the change in school start time, students did not stay up significantly later: They simply slept in longer, a behavior that scientists say is consistent with the natural biological rhythms of adolescents.

 

"Research to date has shown that the circadian rhythms of adolescents are simply fundamentally different from those of adults and children," said lead author Gideon Dunster, a UW doctoral student in biology.

 

In humans, the churnings of our circadian rhythms help our minds and bodies maintain an internal "clock" that tells us when it is time to eat, sleep, rest and work on a world that spins once on its axis approximately every 24 hours. Our genes and external cues from the environment, such as sunlight, combine to create and maintain this steady hum of activity. But the onset of puberty lengthens the circadian cycle in adolescents and also decreases the rhythm's sensitivity to light in the morning. These changes cause teens to fall asleep later each night and wake up later each morning relative to most children and adults.

 

"To ask a teen to be up and alert at 7:30 a.m. is like asking an adult to be active and alert at 5:30 a.m.," said de la Iglesia.

 

Scientists generally recommend that teenagers get eight to 10 hours of sleep each night. But early-morning social obligations -- such as school start times -- force adolescents to either shift their entire sleep schedule earlier on school nights or truncate it. Certain light-emitting devices -- such as smartphones, computers and even lamps with blue-light LED bulbs -- can interfere with circadian rhythms in teens and adults alike, delaying the onset of sleep, de la Iglesia said. According to a survey of youth released in 2017 by the U.S. Centers for Disease Control and Prevention, only one-quarter of high school age adolescents reported sleeping the minimum recommended eight hours each night.

 

"All of the studies of adolescent sleep patterns in the United States are showing that the time at which teens generally fall asleep is biologically determined -- but the time at which they wake up is socially determined," said Dunster. "This has severe consequences for health and well-being, because disrupted circadian rhythms can adversely affect digestion, heart rate, body temperature, immune system function, attention span and mental health."

 

The UW study compared the sleep behaviors of two separate groups of sophomores, all enrolled in biology classes at Roosevelt and Franklin high schools. One group of 92 students, drawn from both schools, wore wrist activity monitors all day for two-week periods in the spring of 2016, when school still started at 7:50 a.m. The wrist monitors collected information about light and activity levels every 15 seconds, but no physiological data about the students. In 2017, about seven months after school start times had shifted later, the researchers had a second group of 88 students -- again drawn from both schools -- wear the wrist activity monitors. Researchers used both the light and motion data in the wrist monitors to determine when the students were awake and asleep. Two teachers at Roosevelt and one at Franklin worked with the UW researchers to carry out the study, which was incorporated into the curriculum of the biology classes. Students in both groups also self-reported their sleep data.

 

The information obtained from the wrist monitors revealed the significant increase in sleep duration, due largely to the effect of sleeping in more on weekdays.

 

"Thirty-four minutes of extra sleep each night is a huge impact to see from a single intervention," said de la Iglesia.

 

The study also revealed other changes beyond additional shut-eye. After the change, the wake-up times for students on weekdays and weekends moved closer together. And their academic performance, at least in the biology course, improved: Final grades were 4.5 percent higher for students who took the class after school start times were pushed back compared with students who took the class when school started earlier. In addition, the number of tardies and first-period absences at Franklin dropped to levels similar to those of Roosevelt students, which showed no difference between pre- and post-change.

 

The researchers hope that their study will help inform ongoing discussions in education circles about school start times. The American Academy of Pediatrics recommended in 2014 that middle and high schools begin instruction no earlier than 8:30 a.m., though most U.S. high schools start the day before then. In 2018, California lawmakers nearly enacted a measure that would ban most high schools from starting class before 8:30 a.m. In 2019, Virginia Beach, home to one of the largest school districts in Virginia, will consider changes to its school start times.

https://www.sciencedaily.com/releases/2018/12/181212140741.htm

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