Lighting Research Center Lighting Research Center
Light & Health

Researching how light can be used to promote health and wellbeing

Every day, more people become interested in the potential benefits of light and dark, especially its effects on human health and wellbeing.

Biological rhythms that repeat approximately every 24 hours are called circadian rhythms. Light is the main stimulus that helps the circadian clock, and thus circadian rhythms, keep a synchronized rhythm with the 24-hour solar day. Humans need to be exposed to a sufficient amount of light for the biological clock to remain synchronized with the solar day. If lack of synchrony or circadian disruption occurs, we may experience decrements in physiological functions, neurobehavioral performance, and sleep.

Lighting characteristics that are effective to the circadian system are different than those effective to the visual system. In order to apply light to mitigate the symptoms of Alzheimer's disease, seasonal affective disorder, jet lag, or sleep deprivation, we need a better understanding of the quantity, spectrum, timing, duration, and distribution of light that is effective for the circadian system. The Light and Health program at the LRC bridges the gap between science and applications by striving to better understand how the visual and circadian systems work and what lighting characteristics affect them.

Circadian stimulus calculator

Sample: Circadian stimulus calculatorThe Lighting Research Center developed a circadian stimulus (CS) calculator to determine CS for any combination of source type and light level in photopic lux. The calculator is available here. This tool was designed to help lighting professionals select light sources and targeted photopic light levels that will increase the potential for circadian light exposure in a building.

Please note that clicking this link will directly download a Microsoft Excel file to your computer or device. You must have the Excel program installed to use the CS calculator. If you have any trouble, please ensure that you have Excel installed and check your download settings.

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