Researchers mostly insinuate the past experiences and trauma that can be the cause of claustrophobia.

An event that could have left some indelible marks that you developed a constant fear of enclosed spaces.

As a child, someone was possibly trapped or confined in a tight space, so the past images have triggered the present phobia.

It could be that whenever the person enters any such place, it resonates with the same picture of the past from which he was scared.

There can be some triggering experiences, like being stuck in an elevator and there was no way to come out.

Then also, there might be the chance of developing this fear.

"Claustrophobia could be related to dysfunction of the amygdala, which is the part of the brain that controls how we process fear." The phobia can also be caused by a traumatic event, such as: being stuck in a tight or crowded space for an extended period of time, experiencing turbulence when flying, being punished by being locked in a small room, like a bathroom, being stuck on crowded public transportation, being left in a tight space, like a closet, by accident.