Artificial lighting from sources as common as streetlights may disrupt the circadian rhythms and immune systems of mammals, and even raise the risk of death, a new study by Tel Aviv University suggests.

Hagar Vardi-Naim, a doctoral student in life sciences, examined the effects of artificial lighting on the immune systems of two related species of small rodent — the golden spiny mouse and the common spiny mouse.

Both live in the Israeli desert and share the same geographical habitat. But while the golden spiny mouse is active during the day, the common spiny mouse operates at night.

The animals were transported from the Judean Desert to outdoor enclosures at Tel Aviv University’s Zoological Research Garden, where some were exposed to artificial light at night.

“Large parts of every mammal’s body, including our own, are regulated by an internal biological clock,” Vardi-Naim explained. “With a 24-hour rhythm based on the natural light-dark cycle, this biological clock signals to various organs and physiological systems, including the immune system, what they should do at different times of day.”

She continued, “For example, the levels of certain white blood cells rise and fall in the blood, and the body produces more or less antibodies at specific times. Such oscillations can enhance the immune response to bacteria or viruses, but for this, the body must know the time.”

She continued, “Light pollution alters the natural light-dark regime, disrupts the central clock’s synchronization with environmental time, and changes these patterns, rendering time almost meaningless.”

The spiny mice were kept in enclosures that simulated natural environmental conditions as far as possible. Half of the enclosures were illuminated at night with white........

© The Times of Israel