# Sleep Duration and Physical Activity as Predictors of Executive Function in Adolescents: A Longitudinal Study

## TL;DR

This study finds that physical activity improves cognitive performance in adolescents, while sleep duration alone does not significantly affect it.

## Contribution

The study provides longitudinal evidence that habitual physical activity, not sleep duration, predicts better executive function in adolescents.

## Key findings

- Higher physical activity predicted faster inhibitory control and fewer attention lapses.
- Sleep duration showed no significant effects on executive function domains.
- In low-activity adolescents, more steps were linked to slower inhibitory control, possibly due to confounding factors.

## Abstract

What are the main findings?
Objective physical activity predicted faster reaction times in inhibitory control and fewer lapses in sustained attention, whereas sleep duration showed no significant effects.In the low-activity subgroup, higher daily steps were unexpectedly associated with slower inhibitory control, possibly reflecting confounding factors or differential physiological adaptation.

Objective physical activity predicted faster reaction times in inhibitory control and fewer lapses in sustained attention, whereas sleep duration showed no significant effects.

In the low-activity subgroup, higher daily steps were unexpectedly associated with slower inhibitory control, possibly reflecting confounding factors or differential physiological adaptation.

What are the implications of the main findings?
Habitual physical activity should be prioritised in educational settings to enhance adolescent cognitive efficiency.Future research must assess circadian timing and sleep variability, rather than relying solely on total sleep duration.

Habitual physical activity should be prioritised in educational settings to enhance adolescent cognitive efficiency.

Future research must assess circadian timing and sleep variability, rather than relying solely on total sleep duration.

Background/Objectives: Adolescence is a critical period for executive function (EF) maturation. While sleep and physical activity (PA) are key lifestyle factors, their longitudinal impact on EF in ecologically valid settings is insufficiently characterised. This study examined the associations between objectively measured sleep duration, daily steps, and EF performance across one academic year (~9 months). Methods: A longitudinal study was conducted with 168 Spanish adolescents (13–16 years). Sleep duration and daily steps were monitored using Fitbit Charge 6 wearables for 7-day periods at baseline (M1; September 2024) and follow-up (M2; June 2025). EFs were assessed using three validated tasks: Stroop (inhibitory control), Psychomotor Vigilance Task-Brief (PVT-B; sustained attention), and Paced Auditory Serial Addition Test (PASAT; working memory). Linear Mixed Models (LMM) were employed to analyse the effects of the fixed factors (i.e., Group and Time), and their interactions. Results: PA, but not sleep duration, significantly predicted executive performance. The High_PA group demonstrated faster reaction times in inhibitory control (p = 0.007) and significantly fewer attentional lapses in sustained attention (p = 0.014). In contrast, sleep duration showed no significant main effects on EF domains (p > 0.05). Regression analyses confirmed that higher daily steps predicted faster reaction times in inhibitory control in the total sample (r = −0.173, p = 0.002), although an unexpected positive association was observed in the Low_PA group for inhibitory control, warranting cautious interpretation. Conclusions: These findings suggest that habitual PA is associated with better EF performance in adolescents, whereas sleep duration alone (without considering timing or variability) showed no significant associations with cognitive outcomes. Sensitivity analyses using clinically informed thresholds and continuous standardised predictors confirmed the robustness of these findings.