P126 The impact of inadequate sleep and breaking up sitting during the day on simulated driving performance

INTRODUCTION: Inadequate sleep and prolonged sitting are both associated with a reduction in psychomotor functioning, a cognitive process crucial for the safety critical task of driving. Regular bouts of light-intensity physical activity have been shown to improve psychomotor function. However, it is unknown if breaking up sitting during the day can improve psychomotor functioning for the task of driving, particularly during the commute home when drivers may be at a higher risk of fatigue. METHOD: Healthy participants (n=81, 49%female, age 23.6 ± 4.5 years ) participated in a 7-day laboratory study (1 adaptation, 5 experimental, 1 recovery). Participants were randomly allocated to a condition: sitting and 9-h sleep (Sit9; n=22), breaking up sitting 9-h sleep (Sit9; n=19), sitting and 5-h sleep (Sit5; n=21) and breaking up sitting 5-h sleep (Break5; n=19). Participants allocated the breaking up sitting conditions completed 3-min of light-intensity walking every 30 minutes between 09:00-17:00h, while participants in the sitting group remained seated. Driving performance was measured via speed and lane variability during a 20-min simulated drive at 08:10 and 17:30 for the 5 experimental days. RESULTS: Mixed model analyses revealed no significant interaction effects between condition and time of commute between Sit9, Break9, Sit5 and Break5 for driving performance. DISCUSSION: Breaking up sitting did not improve driving performance during the commute home. These findings highlight that light-intensity walking may not be adequate to overcome the effects of inadequate sleep on diving performance. Future studies should explore if higher intensity physical activity produce changes in driving performance.