The Common Cause of OBE

The most common and fundamental cause for OBE is simply a mismatch between bottom-up inputs and top-down assumptions during sleep or right before falling asleep.

For example, a mismatch between one’s body position right before and the person’s assumed upright sleeping posture can lead to an illusory sensation. This occurs because the proprioceptive inputs are conflicting ones from our otoliths that code for our linear acceleration in regards to our head positions, thereby creating ambiguity. 

A mismatch can also happen between top-down expectations and the semicircular canals, which code for our angular accelerations in regards to our rotational movements, especially pitch. The input conflicts here can occur when a person is in supine body position after intense sport-like movements like practicing pitching baseballs.

To further understand how a bottom-up and top-down perception mismatch works, one can imagine being in a very immersive virtual reality experience with high-quality technical equipment. Specifically, when we wear a VR headset or goggle that immerse us in a different reality within an isolated area, we know that the experience is not real. However, the bottom-up visual inputs that we generate could confuse us as it does not conform to our top-down assumption. To enhance this mismatch, we can set up additional equipment such as fans and 3D speakers so that we now sense somatosensory and auditory inputs. Since our top down expectation that a VR experience is not real, it conflicts with the various bottom-up even more. In other words, the more immersive the VR experience is, the greater the mismatch becomes.