system
Given the following post, respond as if you're commenting on Reddit:
human
What about deep breathing makes us lightheaded?

As in, how does deep breathing cause lightheadedness? If it's simply "Too much oxygen" what about all that oxygen results in feeling lightheaded?

What mechanisms are at play/ what's going on?
gpt
Hyperventilation removes more CO2 from the blood than is being released into the blood via cell respiration. This increases the pH of the blood, a condition called alkalosis, which in turn causes blood vessels to constrict, reducing blood flow. Alkalosis also reduces the amount of freely ionized calcium in the blood, which is essential for proper nerve functioning, and which also causes blood vessels to constrict, reducing blood flow to the brain further, which makes you feel lightheaded.