Sunlight calls the shots! Why your immune system fights harder in daylight

You’re the opposite of a vampire, you actually get stronger in the sun.

At least, that’s what research suggests. Researchers at the University of Auckland have discovered that daylight boosts the infection-fighting power of neutrophils, the most common white blood cells in our bodies.

Here’s the truth: Neutrophils have their own internal circadian clocks, and these clocks get activated by daylight. When the sun’s out, these immune cells step up their game and become better at killing bacteria. Scientists spotted this by studying transparent zebrafish, yes, see-through fish,  which let them watch these immune cells in action in real time.

Associate Professor Christopher Hall explained it, according to Neuroscience News: Our immune system is tuned to work harder during the day, because that’s when we’re most active and likely to bump into germs. It’s as if our body evolved a smart defense system that knows when to be on high alert.

But why do neutrophils respond to light? Well, many of our cells have circadian clocks to keep track of the day-night cycle, and light is the main cue that resets these clocks. Turns out, neutrophils aren’t just passive fighters, they’re also on the clock, ready to ramp up when daylight hits.

This discovery could really be beneficial: If scientists can find a way to target these clocks inside neutrophils, we might develop new treatments that boost our immunity when we need it most, especially against infections and inflammatory diseases.

Right now, the team is diving deeper to figure out exactly how light flips the switch inside these immune cells. The research, backed by the Royal Society of NZ’s Marsden Fund, could open up exciting new ways to keep us healthier, just by understanding how sunlight helps our immune warriors do their job better.