Why do we get light-headed?

Normally when you get light headed from blowing up a balloon it's from lack of oxygen. You're using all your oxygen to blow up the balloon and it's not going into your lungs, and blood so it will cause you to get light headed. As for when stretching it could very well be that your blood volume is low. In which case you would need to drink some more water, and add a little bit of salt to your diet, but before doing this I strongly suggest you go see a doctor, have them check your blood pressure while sitting, standing, and laying down. Explain to them what is going on, and from that they will be able to correctly diagnose the problem. One thing that is a possibility as well, is that when you stretch if you put your head back it cuts off the circulation to the brain for a bit which can cause the light headed sensation as well. Try to stretch with your head in an upright position and see if the same thing happens. I hope this helps.

There are a couple of different reason why you get light headed. When you stretch you are constriting your blood vessels and there isnt enough blood flow to the brain. This doesnt happen to everyone, but it happens to me and I agree, it sucks. When you blow up a balloon, you get light headed because of lack of oxygen to the brain. If you get up to fast, it happens because your blood pressure isnt stabilizing fast enough so the blood rushes to your feet and out of your head. I get light headed with all of these and have done a ton of research on the internet about it. For the most part that is what I can remember.

It's caused by changing blood flow to or from your brain, if you get up slower and take a few deep breaths this will cut down on it a lot. It's the same when blowing some thing up, any dramatic change in blood flow to or from the brain will cause this sensation! tdemex