Contrasting dynamic light scenarios in an operational office: Effects on visual experience, alertness, cognitive performance, and sleep

In this field study, we tested the effects of dynamic light scenarios and personal illuminance on visual experience, sleepiness, cognitive performance and sleep in an operational office. Two dynamic light scenarios, different in timing but with equal luminous exposure, were tested against a reference scenario in a counterbalanced crossover design. Frequent assessments of visual experience, alertness, performance and sleep showed that in both dynamic light scenarios visual comfort was slightly lower compared to the constant scenario. Additionally, sleepiness was lowest in the scenario with the brighter light timed around noon, whereas task performance and actual sleep were not significantly affected. The measured personal illuminance did not predict sleepiness and performance, yet variation and timing of these illuminances did positively relate to sleep onset and duration. When studying or implementing light scenarios aiming to deliver integrative lighting, the spatial and behavioral context should be considered as well. • Two dynamic light scenarios and a static one were tested in an operational office. • We found subtle effects on subjective sleepiness, but none on task performance. • Visual comfort was higher in the constant scenario than in the dynamic scenarios. • More variability in the personal light exposure was positively related to sleep.