New research from the University of Auckland has revealed that daylight plays a powerful role in helping the immune system fight infections.
The study, led by Associate Professor Christopher Hall and a team of scientists, shows that exposure to light can improve the performance of neutrophils—white blood cells that serve as the body’s first line of defense against harmful bacteria.
Neutrophils are the most common type of immune cells in the body.
They move quickly to the site of infection and destroy invading microbes.
In earlier research, the team noticed that immune responses in zebrafish were stronger in the morning, which is when the fish—and most animals—are more active.
This suggested that the immune system may be more alert and responsive during daylight hours.
To find out why, the researchers studied zebrafish, a small freshwater species often used in science because it shares many biological traits with humans.
What makes zebrafish particularly useful is that they can be genetically modified to have transparent bodies, making it easier to observe immune cells and how they behave.
In their latest study, published in Science Immunology, the researchers discovered that neutrophils have their own internal circadian clocks.
These clocks help the cells recognize what time of day it is, and they boost the cells’ bacteria-killing power during daylight.
Circadian clocks are internal systems that guide the body’s daily rhythms, such as sleep, metabolism, and hormone release—and now, it seems, immunity too.
Since light is the most powerful signal for resetting the circadian clock, this finding helps explain why the immune system may be more effective during the day. It also opens up new possibilities for treatments.
If scientists can find ways to enhance the internal clock of neutrophils, they might be able to develop new therapies that help the body fight infections more efficiently, especially in people with weakened immune systems or chronic inflammatory conditions.
Dr. Hall believes the discovery could be important for many diseases, not just infections. Because neutrophils are among the first cells to respond to inflammation, improving their timing and function could benefit a wide range of health conditions. The team is now working to better understand exactly how light influences the clock inside these immune cells.
In the meantime, this study offers a simple message: spending time in natural daylight could do more than lift your mood—it might also help your body fight off infections.
If you care about inflammation, please read studies about turmeric: nature’s golden answer to inflammation, and what to eat to reduce chronic Inflammation.
For more health information, please see recent studies about how a plant-based diet could help ease inflammation, and Vitamin D deficiency linked to increased inflammation.
Source: University of Auckland.
