Originally Posted by
savethekudzu
My breathing was certainly off today: struggling for breath and stopping frequently as I did when I first began this whole bike-commuting thing. (Years ago I used to get cold-air/exercise-induced asthma, so maybe that's recurring. Never associated it with dizziness before, though.)
Not getting sufficient oxygen will tend to make you dizzy, as can many other things, including but not limited to: dehydration, fatigue, lack of sleep, inner ear disorders, various types of illness, and certain drugs. It could be serious, it could be nothing much -- dizziness per se doesn't tell you.