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：有一种呼吸技巧，一些文献表明它可以激活你的副交感神经系统，它与你吃完饭后睡觉的本能有关。它可以用来减少焦虑，引发放松，并随意入睡。它被称为4-7-8。