Fainting from laughing too hard

We're talking about a woman in her 60s. Every single time she starts laughing—and I mean really losing it—she gets hit with this massive wave of dizziness... Last time, she actually collapsed right onto the floor. She completely lost control...
What could be causing this?

it’s probably because the brain isn't getting nearly enough oxygen, I guess.🤷
when they laugh like that, they aren't even breathing right.