Our perception of reality is shaped by our neurological systems and can be influenced unconsciously. We may act irrationally in response to threats due to instinctual parts of the brain like the amygdala preparing us for "fight or flight" even when threats are not real. It can be difficult to distinguish between reality, dreams, fantasies, and hallucinations as our experiences in these states are governed by similar neurochemical processes. True objective reality may not be knowable.