Is there a scientific explanation to why my hair feels healthier when I use heat?

I have 3A/3B fine hair, and I go through phases where I wear it natural all the time and then phases where I blow it out after every wash (3ish times a week).

I find that during those natural phases, my hair feels less healthy, and feels like I can’t retain length. During the heat styling phases, my hair feels healthier and can grow longer. This goes against everything I’ve ever learned about hair and I’m just curious if anyone else has this experience or if there’s an explanation to it?