Effect of light-off microbreaks on sustained concentration during intellectual work under task-ambient lighting settings

Abstract

When performing tasks that require sustained concentration, task-ambient (TA) lighting, which combines low, uniform ambient illumination with localised task lights, has been recognised as an effective approach to enhance concentration. However, concentration often declines as work progresses, raising the question of whether incorporating recovery opportunities within TA environments can further improve sustained concentration. This study explores the potential of microbreaks, brief pauses that help restore attention before fatigue accumulates, as a strategy suitable for TA lighting settings. A novel intervention, TA with microbreaks (TA-with-MB), was introduced, in which the task light was turned off for 30 s at intervals of 9.5 min, providing a simple yet potentially effective means of recovery. In a controlled laboratory experiment with a within-subjects design, participants performed cognitive tasks for 45 min under two conditions: standard TA and TA-with-MB. Objective concentration was measured using concentration time ratio (CTR), along with subjective assessments of psychological changes. Valid data from 25 participants showed a higher CTR under TA-with-MB than under TA. Subjective evaluations suggested that the intervention enhanced a sense of mental refreshment without disrupting workflow. These findings provide insights into how short-term variations in lighting can function as a promising strategy for enhancing work productivity.