Everyone looks forward to the summer, especially teens. In the United States, this two- to three-month period is typically characterized by sleeping in, catching up on shows and taking part in assorted adventures.
But today’s adventures may be different than those of the past. Just in case parents of today’s teens needed a reminder, we no longer live in the summers of our youth where we played outdoors — likely unsupervised, and certainly without cellphones.
Traditionally, researchers and practitioners focused on physical activity, sedentary behavior (namely, sedentary screen time) and sleep as individual behaviors. More recently, these three behaviors were combined into a single concept christened “24-hour movement behaviors” by a Canadian group in a momentous, multi-behavior step forward. The concept was initially created for children ages 5-17, but similar guidelines have followed for younger children (0-4), and recently adults (18-64) and older adults (65+).
The past decade has produced evidence, mainly cross-sectional, that achieving ideal goals in multiple categories is beneficial for physical and mental health across the lifespan. One of the next steps forward, then, should be to create an intervention or program aimed at improving 24-hour movement behaviors for another distinct age group: teens.
Very few teens meet guidelines for physical activity, sedentary behavior and sleep. In fact, recent systematic reviews demonstrate only ~5% of teens (ages 12-17) meet all three guidelines, and around 30% of teens meet none of them.
Ideally, teens should perform ≥60 minutes/day of moderate-to-vigorous physical activity, including three or more days of muscle-strengthening activities; limit sedentary behavior, particularly recreational screen time, to no more than two hours per day; and sleep 9-11 hours per night (ages 5-13) or 8-10 hours per night (ages 14-17), with consistent bed and wakeup times.
There is clear evidence that all three behaviors change during the summer: in general, adolescents are less active and have higher screen time during this period, and their sleep timing is shifts. These changes are likely due to a lack of pre-planned events or routines, as proposed in the Structured Day Hypothesis and observed during the COVID-19 pandemic.
The home is the one place where all three behaviors occur. Thus, it is also the ideal place to make changes across the 24-hour day. Families, including siblings, may help facilitate more daily physical activity, less screen time and consistent sleep through routines and prioritizing healthy behaviors.
What could a 24-hour program for teens look like?
First, reducing sedentary screen time, given very few teens (~15%) meet this individual guideline. Replacing this time with a physical activity that can be performed close to home, preferably outdoors, is a great place to start. These activities may include family walks, walking the dog, going to a park and helping neighbors with tasks (e.g., mowing the lawn). Outside of the home, it may include a summer camp, volunteering or a part-time job to keep teens off the couch.
Second, creating routines for the whole family. This change may seem counterintuitive with travel and camps cropping up every other week, but everyone (even parents) can benefit from consistent bed and wake times. Proper sleep hygiene, including limiting screens before bed (again, even for parents), may help promote earlier sleep onset.
Third, consider introducing a reward system to promote adherence throughout the summer. Remember, the “prize” should also be a positive, physically active behavior, so think of a trip to a water park or local lake rather than a weekend binging a show.
How do we get started?
Parents: Don’t wait for the new year to make a change. Something as close as the next Monday or beginning of the month is a good time to begin creating routines and promoting healthier behavior. Establishing a program in mid- or late summer can also give teens a head start on these behavior changes before school begins.
Practitioners: Consider assessing sedentary time and sleep as part of evaluations performed during the summer. Promoting adequate amounts of these important behaviors will provide additive benefits beyond those gained from solely focusing on physical activity promotion.
Researchers: Be sure to assess all three behaviors in your current research, and asses through both survey- and device-based measures. Finally, evaluating guidelines amongst longitudinal cohorts will likely improve the predominantly cross-sectional evidence.
Chelsea Kracht, PhD, is an assistant professor in the Division of Physical Activity and Weight Management and Department of Internal Medicine at the University of Kansas Medical Center. Her mission is to conduct research that informs public health initiatives related to child and caregiver health, with specific focus on research that promotes an adequate balance of 24-hour movement behaviors (physical activity, sedentary behavior and sleep) across the lifespan. Dr. Kracht has been an ACSM member since 2015.
