YSK: There is a breathing technique that some literature suggests activates your parasympathetic nervous system, which is tied to your instinct to sleep after eating. It can be used to reduce anxiety, trigger relaxation, and fall asleep at will. It's called 4-7-8.
from /r/YouShouldKnow
YSK：有一種呼吸技巧，一些文獻表明它可以激活你的副交感神經系統，它與你喫完飯後睡覺的本能有關。它可以用來減少焦慮，引發放鬆，並隨意入睡。它被稱爲4-7-8。