Nervous laughter is the result of a psychological defense mechanism that people use to tell themselves that what they see is not as threatening as it appears. It may be that the rhythmic sounds of laughter changed over time to signal a message of safety, according to Psychology Today.
In the field of psychology, some researchers list humor among the mature defense mechanisms that people use to stave off levels of anxiety that are unhealthy. This classification is much safer than the immature, psychotic or neurotic systems. If people can laugh at the awful events in their lives, they are not ignoring them, but instead they are preparing to survive them, as stated by Psychology Today.
When people view an awkward (or awful) event happening to someone else and feel the impulse to laugh, even while they know that laughter is a socially inappropriate response, they are not ridiculing the person suffering. Instead, they are signaling that the awkward incident is not so tragic, and the sufferer has the ability to endure it. In some cases, people need some time after the traumatic event to have the ability to laugh. Some researchers suggest that this delay is necessary to prove to the mind that the trauma was not life-ending, according to Psychology Today.