The Science of Laughing Through the Tears - The Atlantic
Geege Schuman stashed this in The Feels
“If you get into a very high or very low emotion that you're almost to the point of being overwhelmed, you become incapacitated so you can't function well,” Aragón tells me. “Emotional homeostasis is important for people so they can be in control of their cognitive, social, and psychological functions."
In other words, people may laugh when they’re nervous in order to moderate their nervous feelings; likewise, people may cry when they’re happy to recover from distracting giddiness. Aragón speculates that these mismatched expressions also have social purposes: Laughing to the point of excess (or wanting to punch a puppy when you’re overwhelmed by its cuteness) can signal that you've had enough of a certain stimulus and want it to stop.
Tears of sadness vs tears of joy.
Laughing because happy vs laughing because nervous.
Yeah, emotions are confusing.