So I have been paying more attention to where the breakage occurs....

[deedrr]

And I noticed pretty much all of it is happening on the underside of my hair. What causes this and what can I do?

[HintOfMint]

For me, it's friction from rubbing against my back. My worst tangles are in the underside, it's like matted wool. When I detangle it, I'm not always gentle and lo and behold: breakage and splits. I try to keep my hair up when I'm walking around outside, or draped in front of my shoulders. But overall, I just S&D to get rid of splits. My underlayer is always going to be a little shorter as a result, but I'm not hung up on having perfect hair.

[WilfredAllen]

could it be from rubbing on your pillow at night? I wear my hair in a bun on the topof my head at night, and I'm beginning to worry that the backside rubs against my pillow too much

[kidari]

Do you wear your hair down a lot and sleep on your back? I agree that it's friction but also if you wear it down that is usually where all the worst and most tangles form. Just detangling results in some damage. Maybe your pillowcase is rough combined with the way you wear your hair and how you sleep? I'm annoyed with my inability to freely wear my hair down anymore. It took over 3 years of refraining from bad habits and keeping up consistent good ones to get my hair the way it is now. It's annoying to think that the more times I wear it down, the more often I wash it, etc. the more inevitable the consequences will show ugh. This is why I don't have much desire to grow longer sometimes... but only sometimes. Leave-ins do help a lot to help provide slip and protection so that the hair glides over each other and not get so easily tangled. Oils, cones, etc but I prefer coney oil serums. There are some leave-ins with keratin in it as well. Experiment and see what works for you. I hope you find the culprit and a remedy for it soon.