(Photo is mine)
The bat as a symbol has been associated with words like rebirth, intuition, communication, inner depth, initiation, and illusion. For most people, bats have a negative connotation – mostly learned from vampire movies – so a dream of a bat tends to inspire feelings of fear.
Bats symbolize rebirth because they live in cave-like environments and come out in the evening, effectively being “reborn” every night from within Mother Earth. Native Americans considered the bat to be a symbol of communication because bats have strong family ties and are extremely nurturing and social creatures. They are very sensitive to the other members of their group and constantly communicate with them. A dream of a bat suggests issues associated with free will and freedom as well, since bats can fly!
Source: http://sleepculture.com/bat-dream-interpretation-and-meaning/