The following diseases may cause uncontrollable laughter: 1. mania, patients show high emotion, thinking, talking incessantly, high self-esteem, always planning to do great things, and especially happy, happy, when it is easy to appear uncontrollable laughter. 2. mental illness, mainly schizophrenia, patients may appear behavior disorder, especially can not control their own speech and behavior. 3, physical illness, such as hyperthyroidism or endocrine disorders, patients may become particularly happy or even overly excited, may be particularly high state of mind, can not control the laugh, the above reasons are more common.