An example of lightheaded is a potential condition of a person after a concussion.
Felt lightheaded from running.
He sat up, bloodied and lightheaded, unable to quell the power roiling through him.
Lightheaded, Yully sat heavily.
Carmen sank to her chair feeling lightheaded with relief.
Katie was slower to follow, feeling lightheaded once again.
If you start getting lightheaded, that's a bad sign and you should stop.