Zhang Li, even under the influence of the medication and fallen into a sleep state, kept laughing, his laughter ultimately turning into mere "ah, ah" sounds.
After an hour had passed, Zhang Li's laughter finally began to fade away, and he calmed down completely.
This was still Lin Feng showing restraint, utilizing less force and Spirit Essence, otherwise how could Zhang Li's laughter have lasted only an hour?
Breathing through laughter substantially moves the diaphragm, and sustained muscle contractions over time could lead to fatigue, spasms, and even paralysis of the diaphragm, resulting in respiratory failure and eventual death.