The autonomic nervous system (the "involuntary" nervous system) is divided into two branches: sympathetic ("fight-or-flight") and parasympathetic ("rest-and-digest"). Acting via the hypothalamus (left), the sympathetic nervous system is designed to mobilize the body during times of stress. It's why our heart rate quickens, why we sweat, why we don't feel hungry. The parasympathetic nervous system, on the other hand, essentially calms us back down.
You just have to wait. Since such a delicate balance between crying and laughter does not usually last long. The person finds an acceptable solution and calms down.
The autonomic nervous system (the "involuntary" nervous system) is divided into two branches: sympathetic ("fight-or-flight") and parasympathetic ("rest-and-digest"). Acting via the hypothalamus (left), the sympathetic nervous system is designed to mobilize the body during times of stress. It's why our heart rate quickens, why we sweat, why we don't feel hungry. The parasympathetic nervous system, on the other hand, essentially calms us back down.
You just have to wait. Since such a delicate balance between crying and laughter does not usually last long. The person finds an acceptable solution and calms down.
Sometimes when an event occurs, even though it is sad by most counts, you see the irony in it that you start laughing. There you are appreciating the humor in that situation, sometimes referred to as gallows humor. Happy events have led to crying episodes such as in passing an exam with high scores, getting admitted to a university, having your first paper published, being rewarded with a prize, etc. These are tears of joy. Thus it is difficult to predict a priori how the brain is going to interpret a certain stimulus to result in a certain emotional state and subsequent behavior (laugh versus cry.) Past life experiences and memories certainly can impact this.