Lighting colour temperature directly affects alertness and cognitive readiness. Cool-spectrum lighting (5,000K–6,500K) suppresses melatonin and increases alertness — beneficial for active analytical work in the morning and afternoon. Warmer lighting (3,000K–4,000K) is less stimulating — beneficial for extended reading, writing, and reflective work that benefits from lower arousal. HIGHKA’s stepless 3,000K–6,500K adjustability allows users to optimise the lighting for their current task and time of day — replicating the individual control that home workers have and that open-plan offices deny.