Artificial light in your office may affect your health

Recent research indicates that artificial light in office environments could potentially impact human health. A study conducted on animals, specifically Nile grass rats, which are active during the day like humans, found a connection between fluorescent office lighting and weakened daily rhythms, elevated rates of diabetic-range blood glucose, and lower sperm activity compared to those under daylight conditions. However, a single hour of midday light exposure helped to restore these disrupted patterns.

Lily Yan, a coauthor of the study from Michigan State University's psychology department, highlights the importance of understanding how indoor light quality affects physiology. She emphasizes that light is not merely a visual aid; it also functions as a biological signal influencing circadian organization and potentially various downstream health outcomes.

To conduct the study, the researchers utilized programmable spectrum control to replicate real-world lighting conditions and employed Nile grass rats, a diurnal species similar to humans. In the first experiment, eight male grass rats were exposed to four different lighting conditions for two weeks: steady daylight equivalent light, daylight with a dawn-to-dusk pattern, standard fluorescent office light, and office light supplemented with a one-hour midday burst of daylight.

In the second experiment, 20 male grass rats lived under either daylight equivalent or fluorescent lighting for six weeks, with their body weight, blood glucose levels, sperm counts, and sperm motility monitored.

The findings revealed that grass rats living under daylight equivalent lighting exhibited the most robust daily rhythms, while those in the fluorescent office lighting environment demonstrated the weakest daily rhythms. Nevertheless, a single one-hour daylight exposure at midday was found to partially restore the disrupted daily rhythms in the office-lit grass rats.

In the second study, the researchers observed that four out of 10 animals in the fluorescent lighting group developed blood glucose levels that approached the diabetic range, compared to only one out of 10 in the daylight group. Sperm motility was also significantly lower in the fluorescent group, with less than half the motility found in the daylight group. Although sperm counts remained unchanged, the impaired motility consequently affected the sperm's swimming ability.

The interdisciplinary team behind the study, comprising architects, psychologists, and physiologists, views these preliminary findings as promising evidence. However, they advise further investigation using diurnal animals, such as Nile grass rats or other diurnal species, to determine if similar effects occur in humans. Antony Bum Kim, the lead author from UC Berkeley's architecture department, suggests that factors beyond drugs, diet, and exercise, such as the light environments in our homes, schools, and workplaces, are also biological exposures that warrant consideration.

Understanding their effects could help inform healthier indoor environments and identify practical, nonpharmacological methods to support circadian and metabolic health.