Sounds very simple but:
change your bed sheets and pillow case more often
It`s a bit hussle and may seem a bit unmanlybut when you`re cycling, acne is a b*tch for many people, so try it and wait for 3-4 weeks and come back to this thread with results.
How often is "more often"? It depends, of course. The best would be to rotate clean sheets every day, if you can, give it a try for 3-4 weeks.
P.S. Also, if you have back/shoulder acne, see if you can rotate a clean gym shirt and towel more often.
Not a promise, but I hope it helps. It certainly should.
P.S. Now, here`s a flip side. I`m not a scientist but I don`t think anyone should become an obsessive clean-boy. Not to turn this into an essay, but just do some simple googling on humans, exposure, bacteria, dirt, sweat, immune system, ...
Once you know this, you just follow common sense and see what`s good for you.
So that`s what`s up.