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Sleep science: Decoding drowsy driving

cars in traffic

A study published in The Journal of Pediatrics finds an association between a teen’s preference for evening or morning activities, coupled with nightly sleep duration, influences how awake they feel behind the wheel.

Each year, around Daylight Saving Time, we set our clocks forward and reprogram our bodies to adjust to spring. While most people welcome warmer days and lingering daylight, the time transition – and losing an hour of sleep – may leave some feeling jet lag.

For teens, the time transition is even more pronounced. Due to an adolescent’s developing body and a release of hormones to support growth and development, their biological clock is naturally set for late-evening bedtimes. Getting enough sleep is tough, especially with packed activity schedules and early-morning school start times.

A new study in The Journal of Pediatrics finds the impact of student sleep deprivation extends past feeling alert in class. Almost half of teen drivers surveyed – 205 out of 431 – from Fairfax County Public Schools reported driving drowsy at least once during the 2015 school year, the study period. Out of the 431-person sample, 63.1 percent of respondents reported driving several times a week. One-third of participants drove every day.

Helping teens feel alert behind the wheel is two-fold: Healthy school start times, those starting at 8:30 a.m. or later, help. Getting enough sleep is critical. The researchers also found that a student’s chronotype, or their preference for morning or evening activities, based on the Morningness-Eveningness Scale for Children, factor into drowsy driving:

  • Students with an evening chronotype, or preference for evening activities, coupled with shorter school-night sleep duration, were more likely to experience sleep-impaired driving.
  • Students with a morning chronotype, and who got at least eight hours of sleep, had the lowest prevalence of drowsy driving.
  • Compared with students who slept for at least eight hours on school nights, those who slept for less than seven hours had a 13.9 percent higher prevalence of drowsy driving.
  • The mean age of students surveyed was 16.9 years. The mean range of school-night sleep was seven hours.

Daniel Lewin, Ph.D., associate director of sleep medicine at Children’s National Health System, encourages schools to adopt later school start times, which Fairfax County Public Schools did, and he encourages students and families to assess their sleep patterns – focusing not just on sleep quantity but on sleep quality. His advice for families or students hesitant to change is to start small.

Try a seven-day challenge: Sleep on a regular schedule, sleep for recommended amounts of time, based on age-appropriate guidelines, cut out naps and eliminate late-afternoon caffeine intake.

Most children and families will start to notice the immediate benefits of getting a good night’s sleep, especially throughout the week: less daytime sleepiness, happier moods, improved eating habits and feeling more alert behind the wheel, which impacts driver safety – and not just for teen drivers but for parents, teachers and everyone on the road.

general school supplies

Studying the impact of later school start times

general school supplies

Teens have a biological preference to fall asleep later than younger children and adults, and wake up later, due to a delayed release of hormones that promote sleep. This timing coincides with puberty and makes it harder for middle and high school students to fall asleep early – regardless of 5 a.m. alarms and 7:17 a.m. school start times.

After studying this trend among nearly 1,000 seventh and eighth-grade students in 11 middle schools within a Mid-Atlantic school district, Daniel Lewin, Ph.D., a sleep medicine specialist, pediatric psychologist and associate director of the sleep medicine program at Children’s National Health System, coauthored and published research entitled “Later Start, Longer Sleep: Implications of Middle School Start Times” in the Journal of School Health, which outlines the benefits of delaying school start times.

The research team divided students into two groups: Close to 650 students attended eight late-starting middle schools, where school started at 8 a.m., while nearly 350 students attended early-starting middle schools, where school started at 7:23 a.m.

Students starting school 37 minutes later, despite going to bed 15 minutes later than peers attending an earlier-starting school, got 17 minutes more sleep each night and were more likely to report feeling wide awake during class. The researchers predicted this later-starting school model would translate to students getting an extra 75 minutes of sleep a week – roughly 51 hours of extra sleep each school year. These researchers find that every two minutes in delayed school start times results in one minute of additional sleep each night for children and teens.

Sleep Chart

Middle and high school students should get 8.5 to 10.5 hours of sleep each night, ideally between 9 p.m. and 8:30 a.m. for 12- to 15-year-olds and 10:30 p.m. and 9 a.m. for 16- to 18-year-olds.

The American Academy of Pediatrics (AAP) published similar research in their journal, Pediatrics, about the benefits of letting teens catch up on sleep, citing a reduced risk of students being overweight, getting into car accidents or suffering from depression as well as a greater likelihood of having better grades, higher test scores and a better quality of life. AAP recommends schools start at 8:30 a.m. or later to allow students to get 8.5 to 9.5 hours of sleep each night and issued a statement in 2014, entitled “School Start Times for Adolescents.”

Dr. Lewin continues to track these benefits and works with schools to implement the changes. He recently wrote an editorial, entitled “All the Clocks Are Ticking: Sleep Health and Metabolism,” for the Journal of Adolescent Health about the correlation between improved sleep health, mental and physical health and academic performance, explaining how circadian clocks, present on a cellular level, influence behavior and metabolism.

While pushing school start times back requires an immediate investment of rearranging travel routes, bell schedules and after-school activities, several school districts near Washington, D.C., from Virginia Beach to Fairfax County, are adopting this public health model.

An economic analysis conducted by the RAND Corporation finds that after two years, the benefits of reorganizing school start times outweigh the costs.

Young girl sleeping

Is actigraphy helpful for assessing sleep-wake disorders?

Young girl sleeping

The second most-read article in 2018 in the Journal of Clinical Sleep Medicine, published by the American Academy of Sleep Medicine (AASM), was about using actigraphy to evaluate sleep disorders and circadian rhythm sleep-wake disorders.

FDA-approved actigraphy devices are typically kept on the wrist or ankle and track movement activity, which researchers can use as part of a larger toolset to analyze how much activity occurs right before and during sleep.

The AASM guidelines, entitled “Use of Actigraphy for the Evaluation of Sleep Disorders and Circadian Rhythm Sleep-Wake Disorders: An American Academy of Sleep Medicine Clinical Practice Guideline,” included the AASM’s stance on clinical recommendations for children and adults, rated as strong or conditional.

The conditions for evaluating pediatric health conditions are as follows:

  1. The AASM suggests that clinicians use actigraphy in the assessment of pediatric patients with insomnia disorder. (Conditional)
  2. The AASM suggests that clinicians use actigraphy in the assessment of pediatric patients with circadian rhythm sleep-wake disorder. (Conditional)
  3. The AASM suggests that clinicians use actigraphy to monitor total sleep time prior to testing with the Multiple Sleep Latency Test in adult and pediatric patients with suspected central disorders of hypersomnolence. (Conditional)
  4. The AASM recommends that clinicians not use actigraphy in place of electromyography for the diagnosis of periodic limb movement disorder in adult and pediatric patients. (Strong)

In an interview with Neurology Today, Daniel Lewin, Ph.D., a sleep medicine specialist, pediatric psychologist and associate director of the sleep medicine program at Children’s National Health System, offered advice, alongside other sleep medicine experts, about the new guidelines:

“It’s a very powerful tool, but it does require some knowledge of basic sleep mechanisms and of how the tool can be used and what variables can be extracted from the tool,” Dr. Lewin said in the interview with Susan Kreimer.

Anne Goldstein, M.D., M.S., assistant professor of neurology at the University of Michigan Sleep Disorders Center, tells Kreimer that “Actigraphy records only movement and that non-moving is often misinterpreted as sleep.”

Dr. Lewin has used actigraphy in sleep research studies but notes the use of these devices come with extensive training. Other researchers expressed similar sentiments with Neurology Today, noting the value of the sleep assessment tool to capture preliminary sleep behavior assessments, similar to a self-reported sleep log, while noting their limitations, such as capturing sleep patterns over extended periods of time, instead of in 14-day increments.

“When you’re living a typical active human life, sleep can wax and wane, depending on travel patterns, work responsibilities and stress levels,” Nathaniel F. Watson, M.D., professor of neurology at the University of Washington School of Medicine in Seattle and director of the UW Medicine Sleep Clinic, tells Kreimer. “This variability in sleep highlights the need for additional technologies capable of assessing sleep over longer periods of time.”

Read about other researcher’s perspectives captured by Susan Kreimer for Neurology Today.

smiling baby sleeping

The science behind optimal sleep health

smiling baby sleeping

Children younger than age 2 need at least 12 hours of sleep each day.

As families and parents renew their interest in health in the new year, pediatricians can take advantage of this momentum by talking about one area absent from common New Year’s resolutions lists: getting enough sleep.

Like diet, exercise and activities that keep your brain sharp, such as reading or learning a new language, healthful sleep patterns play a vital role in supporting physical health and cognitive performance – especially for children and teens.

Here are a few tips parents and pediatricians can use, based on research published by Daniel Lewin, Ph.D., a pediatric psychologist and sleep medicine specialist at Children’s National Health System.

Understand how much sleep each child needs.

The typical range of recommended sleep, such as eight to 10 hours each night, varies for each child. A 16-year-old may do well with 8.5 hours of sleep, while a 6-year-old may need 13 hours of sleep to stay alert. Their body is still rapidly developing. The timing of sleep matters, too, due to a child’s natural circadian rhythm. A chart below details sleep recommendations based on age.

Sleep Chart

Turn a child’s bedroom into a healthful sleep chamber.

Encouraging children to fall asleep by 7 or 9 p.m. may require planning – outside of maintaining regular sleep schedules. To start, make it easy to promote sound sleep by eliminating distractions, including clocks and electronic devices, which might sit next to a child’s bed and distract him or her from getting a good night’s sleep.

Reserve a designated area for homework and study hours outside of the bedroom, which helps reinforce that the bed is a place for sleep and rest. Avoid doing any complicated routines or activities that might cause excitement right before bed, such as assembling a new toy or playing a high-stakes game.

Follow the same rules for conversations: Don’t have talks that might evoke excitement, like the next Disneyworld vacation, or stress, such as bringing the next day’s spelling test up right before bed. By creating a calm zone, you’ll avoid energizing the biological ‘burst zone,’ a rush of energy that occurs in short bursts before one prepares to rest for the night. Keep conversations and routines simple and soothing. Reading, stretching or practicing mindfulness and yoga are complementary activities children can practice at least 15 minutes before bedtime.

Schedule activities about circadian rhythms.

Understanding when a child sleeps best is just as important as understanding how much sleep is essential to support optimal health. A student in high school is biologically wired to stay up past 9 p.m. due to a later release of hormones that promote sleep. This is one reason some school systems are experimenting with later middle and high school start times, which, according to a review in the Journal of School Health, increases a student’s chance of feeling ‘wide awake’ and alert in the classroom.

If you have control of your student’s schedule, plan around it. For instance, schedule activities for a 17-year-old in the late morning, if possible, while allowing time in the afternoon for a young child to take a nap.

These starter tips serve as ways to strengthen sleep quality. Learn more about Dr. Lewin’s research at PubMed, view a few of his blogs for parents at U.S. News & World Report and learn about the link between sleep and health at the National Institutes of Health. If you experience recurring problems, such as sleep apnea, insomnia, sleep walking, ongoing sleep disruptions or excessive daytime sleepiness, connect with a health care provider.