No need to wonder. This is studied and well-documented.

Mark Kelley's brother Scott is a living case study:

https://www.nationalgeographic.com/science/article/study-of-astronaut-twins-hints-at-spaceflight-health-effects#:~:text=Researchers%20also%20found%20abnormalities%20such,and%20in%20his%20carotid%20artery.

Here are a couple of articles:

NASA https://www.nasa.gov/humans-in-space/the-human-body-in-space/

Baylor College of Medicine https://www.bcm.edu/academic-centers/space-medicine/translational-research-institute/space-health-resources/how-the-body-changes-in-space#:~:text=Space%20Radiation,-While%20on%20Earth&text=They%20can%20experience%20radiation%20sickness,to%20about%20100%20times%20that.