To enhance intellectual productivity, this study investigates the impact of dynamic lighting changes intended to induce micro-refreshment (MR) on concentration. We conducted a trial experiment where two participants performed a cognitive task under two conditions: one with constant task-and-ambient lighting designed for focus, and another where the lighting switched every five minutes for 30 seconds to a high-illuminance environment intended for refreshment and MR. We measured performance using the Concentration Time Ratio (CTR) and collected subjective feedback through questionnaires and interviews. The results showed that the lighting change condition decreased CTR by over 5% for both participants. Subjective reports also indicated lower concentration and higher fatigue, without refreshment benefits. Participants found the MR lighting to be glaringly bright and the switching frequency too disruptive for sustained focus. We conclude that while this specific intervention was counterproductive, the findings highlight critical parameters, stimulus intensity and timing, that must be carefully calibrated. The positive feedback on the baseline task-and-ambient lighting confirms its effectiveness. Future work will refine the lighting changes based on these insights to better support intellectual work.