well lately, i've been riding quite a bit. it's kind of cold outside, and i wear a bandana over my nose and mouth to keep my throat warm. anyhow, my o2 intake is restricted a bit from doing that, and i figure it should help my body utilize o2 more efficiently (just to justify to for myself for doing what i am doing). now, i do not know if this might be bad for me or not. i do get a bit light headed, but it feels pretty good after the ride when i get to breathe all the o2 i can get. any thoughts? will i be okay for doing this? is it actually helping my body be more efficient? am i killing my brain cells?