I used to run long distance. I'd have to go for 15+km in a single session to get any noticeable impact on sleep and it wasn't huge. Weightlifting on the other

I used to run long distance. I'd have to go for 15+km in a single session to get any noticeable impact on sleep and it wasn't huge. Weightlifting on the other hand... a solid hour of going heavy will put me out like a baby every time. I'm very curious why. Am I just built for long distance running and NOT for building muscle?