Outdoor play is good — but the time of day flips the direction of its effect on a child’s emotion regulation.
Introduction: The Blank Space in “Let Them Play a Lot Outside”
“Children should run around outside as much as possible.” Everyone has heard the advice. Plenty of studies link outdoor play to cognitive development and emotional stability, so parents take their kids to parks and playgrounds whenever they can. Before morning drop-off, after dinner, all weekend morning — anywhere “outside” is taken to be a good thing.
But this advice has a blank in it. It focuses entirely on how many minutes, and almost never asks at what time of day.
A recent study from the U.S. Midwest filled that blank. The result was striking enough to overturn intuition: the same amount of outdoor play, given at different times of day, had opposite effects on a child’s emotion regulation.
The Core Research Question
The team (a Midwestern U.S. university) asked a simple but tricky question:
“Does the effect of outdoor play on a child’s emotion regulation depend on the time of day? If so, what cognitive mechanism mediates the path?”
Three things were checked:
- How does outdoor play in the morning, midday, and evening each relate to a child’s negative emotional lability (how often, how big, and how negative the emotional swings are)?
- If outdoor play affects emotion regulation, does it pass through working memory?
- Of the three windows, which one boosts working memory?
Study Design and Participants
- Participants: 325 preschoolers (mean age 4.19 years, SD 0.85)
- Family background: Low-income U.S. Midwestern families (income-to-needs ratio 0.67 — below the poverty line)
- Race: 72.6% African American, 13.6% mixed, 10.4% White
- Recruitment: Through Head Start and social service agencies; 82.3% were enrolled in daytime preschool
- Follow-up: 6 months
- Analysis: Mediation analysis using the PROCESS macro
How It Was Measured
Outdoor play — split into three windows
Parents completed an Outdoor Time Checklist, reporting how many minutes their child spent outside in each of three windows:
- Wake-up to noon
- Noon to 6 PM
- 6 PM to bedtime
For each window they chose: 0 minutes, 1–15, 16–30, 31–60, or more than 60 minutes.
Emotion regulation — how much it swings, how negative the swings are
The 15-item Lability/Negativity subscale of the Emotion Regulation Checklist was used. This scale combines two components into one score: Lability — how quickly and unpredictably emotions change; Negativity — how often those swings tilt negative (anger, irritation, crying). A higher score means emotions swing easily, broadly, and toward the negative. We’ll call this “negative emotional lability” for short.
The mediator: working memory — the mind’s workbench
Working memory is the ability to hold a few pieces of information in mind for a short time and operate on them. Unlike short-term memory, which simply stores, working memory thinks on top of what it stores. In a young child it shows up when carrying out “take off your shoes, wash your hands, then come” in order, or holding board-game rules in mind while taking a turn.
It’s directly tied to emotion regulation. When angry, holding the rule “no hitting” in mind + suppressing the impulse + selecting an alternative behavior all require this workbench. A small bench means the child gets dragged by impulse; a wider bench creates room to pause and choose. That is why working memory was set up as the mediator linking outdoor play to emotion regulation.
The team measured working memory with the WPPSI (Wechsler Preschool and Primary Scale of Intelligence) working memory composite, age-standardized.
Results: Same Outdoor Play, Opposite Direction by Time of Day
Noon to 6 PM outdoor play: beneficial
The more outdoor time in this window, the lower the child’s negative emotional lability — emotions swung less and negative reactions were less frequent.
- Direct effect: b = −0.70, p < .05
- The effect was fully mediated by working memory: midday outdoor play improved working memory, and the improved working memory improved emotion regulation.
- Indirect effect: b = −0.13, 95% CI [−0.30, −0.01]
Wake-up to noon: increased negative emotional lability
- Direct effect: b = 0.83, p < .01
- More morning outdoor time, higher negative emotional lability.
- No mediation through working memory.
6 PM to bedtime: also increased negative emotional lability
- Direct effect: b = 0.86, p < .01
- Evening outdoor play moved in the opposite direction from midday.
- Again, no working memory mediation.
The full model explained 17% of the variance (R² = 0.17) in emotion regulation.
A hidden fact: when the children were actually playing
- Before noon, 40.6% of children had 0 minutes outdoors
- After 6 PM, 44.4% had 0 minutes outdoors
- Between noon and 6 PM, 20.6% had 0 minutes outdoors
In other words, most children were not getting outside during the “beneficial” daytime window. Many of those who did go out were outdoors in the morning or evening — exactly when outdoor play correlated with greater emotional lability.
Why Was Only Midday a Medicine, While Morning and Evening Became a Poison?
The team’s main hypothesis is alignment with circadian rhythm.
“Sunlight exposure and activity centered around midday line up with a child’s biological clock and contribute cumulatively to cognitive and emotional function. Activity early in the morning or after sunset can disrupt that rhythm and make emotion regulation harder.”
A simple analogy: outdoor time may be less about “how much” and more about “whether sunlight and activity arrive when the body’s clock is open.”
Several supporting interpretations are also possible:
- Evening outdoor play → child goes to sleep aroused → poorer sleep → next day’s emotional lability rises. Sleep is the foundation of emotion regulation, so anything that erodes it has large indirect effects.
- Morning outdoor play that crowds the school commute, breakfast, and routine can leave a child starting the day rushed and emotionally unstable.
- These interpretations were not directly tested in this study. What the data show is the correlation between “where outside the child was, by time window” and “the emotional lability score.”
Crucially, the working-memory pathway operated only in the midday window. Morning and evening outdoor play did not raise working memory, so they didn’t get the “working memory → emotion regulation” benefit either.
Practical Implications
1. “When you go out” may matter as much as “how long you go out”
Rather than “we got 30 minutes outside today, we’re done,” the key may be to secure the right time window first. Especially the noon-to-6 PM window favored both emotion regulation and cognition.
2. Outdoor play after sunset deserves a second thought
If after-dinner playground walks are the routine, consider moving the time slot earlier or substituting an indoor activity. If high-arousal play in the 1–2 hours before bed is habitual, sleep patterns are the place to start.
3. Build daytime outdoor activity into the structure of the day
In the study sample, one in five children spent zero minutes outdoors during the daytime window. Preschool outdoor periods, post-pickup park visits, weekend afternoon outdoor plans — daytime outdoor activity needs to be structurally embedded in the routine, not left to the leftover hours.
Limitations
The study made an important contribution but also has clear constraints:
- Observational, not experimental. Time-of-day exposure was not randomly assigned, so causal direction can’t be confirmed. It is possible that parents of children who already had emotion-regulation difficulties took them out in the morning or evening to “burn off energy.”
- Measurement timing. Outdoor play was measured only at Time 1 and emotion regulation only at Time 2. Both variables’ over-time changes were not tracked simultaneously.
- Sample bias toward region and SES. Low-income Midwestern U.S. families with a specific racial composition. Neighborhoods, parental supervision style, and play-environment quality may differ in other groups.
- Data collected 2009–2014, when screen use was very different from today.
- Parent report, not GPS or accelerometer-based objective measurement.
- Quality of play wasn’t differentiated: nature vs. playground, with peers vs. alone, etc., were not analyzed.
Closing
The message of this study is unexpected but simple:
Outdoor play is good, but when you are outside changes the direction of its effect — and the path that creates the difference runs through working memory.
A more accurate version of “let them play outside more” might be “when you can, protect the daytime window.” Sometimes science doesn’t overturn intuition so much as give it precise coordinates. This is one of those cases.
Source: Lee, J. J., Flouri, E., & Jackson, Y. (2024). The role of timing and amount of outdoor play in emotional dysregulation in preschool children. Child: Care, Health and Development, 51(1), e70020. https://doi.org/10.1111/cch.70020