Has always worked for me also. I'll add that if a building fever is involved, I stay off the bike. Also, som 'head colds' seem to involve the inner ear fluid and seem to affect balance. I've actually been 'fighting' some lowgrade thing since last Friday, and Monday and Wednesday I've felt some inner ear/balance issues. Stayed off those days. Did a real easy 20 yesterday and a moderate tempo 30 today, feeling abit better, but still not 'over' it.
A liberal application of Belgian Dark Chocolate also seems to help