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Effects of temporal light modulation on workers’ cognitive performance, mental workload and well-being

Project number: F 2534 Institution: Federal Institute for Occupational Safety and Health (BAuA) Status: Ongoing Project Planned end: 2024-09-30


It is becoming less common for workplaces to be illuminated with traditional light sources. At the same time the increasing use of light-emitting diodes (LEDs) is leading to the application of new lighting functions, such as dimming, optical data transmission, and circadian daylight simulation. These functions are frequently accompanied by light modulations – usually referred to as flicker –, the effects of which on humans are not yet sufficiently understood.

It is generally accepted that the existing occupational health and safety legislation protects employees from known hazards caused by light modulations like flickering. However, there are still gaps in what is known about how they influence visual processes and activities that require workers to concentrate hard for sustained periods. The evidence currently available does not appear robust enough, especially with regard to the frequently encountered light dimming systems that use pulse-width modulation (PWM) and new, light-based data transmission technologies. However, the scientific studies that have been published suggest even fast, and therefore invisible, flickering may put individuals under strain because it is still registered by the sensory and nervous system. Visual perception and cognitive processes may be altered, and raised stress levels may be the consequence.

This project will be conducted as a human subject laboratory study applying established testing procedures, including modern neurophysiological methods. It will investigate the effects of light modulations on cognitive performance, mental strain, and employee well-being with the aim of expanding the knowledge base for the safe use of dimmable and controlled lighting in the workplace.


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