Maybe it's my imagination, but since getting into cycling I'm sure I get more head rushes

Not a problem whilst riding, but in general around the house I get light-headed when I stand up, run up stairs, etc... I think this is getting more common as I do more and more cycling, but maybe I'm reading to much into it? I have stepped up my frequency, distances and performace recently, if that makes a difference...

Any thoughts?

Thank you!