How much sleep do teenagers need?

In a new study published in Child Development, Andrew J Fuligni and colleagues examined whether there is an “optimal” amount of sleep for peak levels of academic achievement and mental health in teenagers.

A total of 421 pupils (mean age = 15.03 years) with Mexican-American backgrounds from the 9th and 10th grades (Years 10 and 11) of two high schools in the Los Angeles area reported the amount of sleep they had every night for two weeks. Official school records were obtained at the end of the academic year to measure academic achievement. The Youth Self-Report form of the Child Behavior Checklist was used as a measure of mental health. A year later, 80% repeated the same process and a second wave of data was collected.

Pupils who averaged 8.75 – 9 hours of sleep per school night demonstrated peak levels of mental health, whereas those who averaged 7 – 7.5 hours of sleep per night had the highest levels of academic achievement (see also an earlier study reported in Best Evidence in Brief).

While the results showed that the “optimal” amount of sleep needed is different for the two developmental outcomes, the researchers note that reducing sleep for the sake of academic performance may result in a greater decline in mental health than in the decline in academic performance from increasing sleep for the sake of mental health.

Source: Adolescent sleep duration, variability, and peak levels of achievement and mental health (January 2017), Child Development DOI: 10.1111/cdev.12729

Do sleep problems in early childhood predict performance at school?

A study published in the British Journal of Educational Psychology looks at whether problems with sleep and self-regulation might be used to predict how children settle in at school.

The study involved 2,880 children from Growing Up in Australia: The Longitudinal Study of Australian Children. Child sleep problems and emotional self-regulation were assessed via reports from mothers at three time points between birth and age five. Child attentional regulation was assessed by the mothers at two time points, and school adjustment was measured by teacher reports of classroom self-regulation and social, emotional, and behavioural adjustment at school, when the children were aged 6-7 years.

Three profiles were found. A normative profile (69% of children) had consistently average or higher emotional and attentional regulation scores and sleep problems that steadily reduced from birth to five. The remaining 31% of children were members of two non-normative profiles, both characterised by escalating sleep problems across early childhood and below mean self-regulation. Children in the non-normative group were associated with higher teacher-reported hyperactivity and emotional problems, and poorer classroom self-regulation and prosocial skills.

The researchers conclude that early childhood profiles of self-regulation that include sleep problems offer a way to identify children at risk of poor school adjustment. Children with escalating early childhood sleep problems could be an important group for interventions to support transition into school.
Source: Early Childhood Profiles Of Sleep Problems And Self-Regulation Predict Later School Adjustment (2016), British Journal of Educational Psychology.

Later starts for teenagers could improve achievement and safety

In 2014, The American Academy of Pediatrics (AAP) recommended that secondary schools start no earlier than 8.30am to accommodate teenagers’ changing biological sleep cycles, which dictate later sleeping and waking times. The AAP cited studies finding that teenagers who don’t get enough sleep demonstrate poor academic performance and a higher risk of road accidents. Furthermore, getting the nine hours of sleep recommended for teenagers becomes a challenge in adolescence when sleep cycles make it difficult for them to fall asleep before 11pm.

A group of sleep researchers from Harvard University, Oxford University, and the University of Nevada recently made their own recommendations that school start times for teenagers should synchronise with their biology, ideally calling for classes to start at 10am for 16-year-olds and 11am for 18-year-olds. They stated that a 7am wake time for teenagers is equivalent to a 4.30am wake time for a teacher in their 50s. The authors explained that the biological changes requiring teenagers to both sleep and wake later coupled with the early start times of most schools in the US leads to 2-3 hours of sleep loss every day. This amount of sleep deprivation hinders memory, metabolism, and psychological health.

The authors describe several studies of later start times, which consistently show health and academic benefits for pupils. They urge policy makers to consider that later start times are less expensive to implement than most other interventions to improve teenage health and academic achievement.

Source: Synchronizing Education to Adolescent Biology: ‘Let Teens Sleep, Start School Later’ (2015), Learning, Media and Technology, 40(2).

Are children getting enough good-quality sleep?

A new research brief from Child Trends looks at the evidence on children’s sleep habits and their well-being and development. After reviewing data from various sources such as the US Bureau of Labor Statistics, the National Sleep Foundation, and several journal articles, Child Trends offers the following conclusions:

  1. Most children are getting adequate sleep. There is no consistent evidence that children or adolescents are getting less sleep now than in the past; in fact, adolescents and young adults report somewhat more hours of sleep now than they did a decade ago.
  2. Sleepiness can be a warning sign. There is good evidence that sleepiness, regardless of its origins, puts children and young people at risk of unintentional injuries and, for adolescents who are drivers, increases the likelihood of road accidents.
  3. The relationship between short sleep duration and being overweight is controversial. There is sufficient evidence for a number of researchers to recommend that we look seriously at improving sleep as a strategy for preventing obesity.
  4. Use of electronic media, particularly in the bedroom, can lead to poor-quality sleep. Children’s use of mobile phones, tablets, computers, and TV close to bedtime, and especially having such media in their bedroom, is associated with poor-quality sleep.
  5. Adolescents may benefit from later school start-times. Preliminary evidence shows that later start times are associated with improved attendance, discipline, alertness, mood, and health.

Source: Five Things to Know about Children and Sleep (2014), Child Trends.

… so let them have a lie-in

This report from the University of Minnesota presents findings from a three-year study on high school (age 14-18) start times. It examined whether or not a delay in start times had an impact on students’ overall health and academic performance.

The study consisted of three parts:

  • Collecting survey data from over 9,000 students across eight high schools in five school districts. Students were individually surveyed about their daily activities, substance use, and sleep habits.
  • Collecting data on students’ academic performance, such as grades earned, attendance, timekeeping, and performance on state and national tests. The researchers also examined car crash data for the communities involved in the project.
  • An examination of the processes by which local school districts made the decision to change to a later start time.

Key findings included:

  • High schools that start at 8:30am or later allow for more than 60% of students to obtain at least eight hours of sleep per school night;
  • Teens getting less than eight hours of sleep reported significantly higher depression symptoms, greater use of caffeine, and are at greater risk for making poor choices for substance use;
  • Academic performance outcomes, including grades earned in core subject areas of mathematics, English, science, and social studies, plus performance on state and national achievement tests, attendance rates, and reduced tardiness, show significantly positive improvement with the start times of 8:35am or later; and
  • The number of car crashes for teen drivers from 16 to 18 years of age was significantly reduced (by 70%) when a school shifted start times from 7:35am to 8:55am.

Source: Examining the Impact of Later High School Start Times on the Health and Academic Performance of High School Students: A Multi-Site Study (2014), University of Minnesota.

Healthy relationships send teenagers to sleep

What has the largest influence on teenagers’ sleep habits? A study published in the Journal of Health and Social Behaviors explored this topic and found that social factors (eg, relationships with parents and peers) outperform developmental factors (eg, the timing of puberty and resultant drops in melatonin) in determining sleep patterns.

The study draws on the Study of Early Child Care and Youth Development, a longitudinal study of children’s physical, cognitive, and social development. The sample was 974 teenagers who reported on their own sleep habits at ages 12 and 15. They also reported on social ties (eg, parental support, peer relationships), academic demands, and daily schedules, and their mothers reported on family structure and children’s physical development.

Findings showed that as children age from Year 7 to age 15, sleep duration on a school night declines from more than nine to a little less than eight hours per night, and reports of disrupted sleep increase over the interval. Generally, stressful social ties (eg, when family composition changes because of divorce or remarriage) were shown to disrupt sleep. Teenagers had healthier sleep (longer duration and of higher quality) when social ties were a source of support, such as when they felt part of the schools they attended or they were surrounded by academically oriented and prosocial friends.

Source: Social Ties and Adolescent Sleep Disruption (2013), Journal of Health and Social Behaviors, 54(4).