system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why people recommend breathing in a bag when nervous.
gpt
The bag traps some of the carbon dioxide that you're exhaling. Carbon dioxide levels in the bloodstream tend to lower when you feel stressed out or anxious. Breathing in some of that recycled co2 will raise the level in your blood, making you feel better and more balanced.