Why you fight infection better in the daytime

Depending on what time it is, your body responds differently to an injury or infection. During the day, you're likely to heal faster and fight infection better than at night. And historically, scientists weren't entirely sure why. That picture is starting to clear up thanks to a new study published last week in the journal Science Immunology. The research finds a missing piece of the puzzle in neutrophils, powerful immune cells that — despite living less than 24 hours — know the difference between day and night.Got a question about how the body works? Let us know at shortwave@npr.org. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.

May 30, 2025 - 08:22
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Why you fight infection better in the daytime
A group of researchers primarily based at the University of Auckland in New Zealand set out to study neutrophils, a type of immune cell. After watching how fluorescent bacteria interacted with fluorescent neutrophils in transparent baby zebrafish, they found that the immune cells can indeed tell whether it

Depending on what time it is, your body responds differently to an injury or infection. During the day, you're likely to heal faster and fight infection better than at night. And historically, scientists weren't entirely sure why. That picture is starting to clear up thanks to a new study published last week in the journal Science Immunology. The research finds a missing piece of the puzzle in neutrophils, powerful immune cells that — despite living less than 24 hours — know the difference between day and night.

Got a question about how the body works? Let us know at shortwave@npr.org.

Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at
plus.npr.org/shortwave.

(Image credit: matheesaengkaew)