This study investigated the non-image forming (NIF) effects of dynamic light on alertness,
cognitive performance and mood on mental fatigue, as well as moderation of task
difficulty in lighting perception. Sixteen participants completed a psychomotor vigilance
test (PVT) and two complex cognitive tasks (multi-attribute task battery-II (MATB-II) and
n-back) with low, medium and high difficulty levels under dynamic (4000 to 12000K,
melanopic equivalent daylight illuminance (EDI)=224lx to 420lx) and static (4000K,
melanopic EDI=224lx) lighting with illuminance set at 500lx on the desk. Psychological,
behavioural, biochemical and electrophysiological responses to light were assessed.
The results showed that exposure to dynamic light had significant benefits on subjective
sleepiness, positive mood and task performance, which may be moderated by task
difficulty. The intervention effect of dynamic light on fatigue was also found during an
electrophysiological activity due to increase in the amount of attentional resources
allocated to the tasks by dynamic light, but was not observed in biochemical measures.
Y Li , W Fang, B Guo and H Qiu, Diurnal effects of dynamic lighting on alertness, cognition, and mood of mentally fatigued individuals in a daylight deprived environment,Lighting Res. Technol. 2022; XX: 1–20,doi.org/10.1177/14771535221138589