Virtual reality sickness is a feeling of discomfort or disorientation that can occur when experiencing virtual environments. There are several theories on its causes, mostly related to the small but noticeable gap between virtual reality and reality. One theory is that the difference between the actions of the user in real life and what they see in VR gives them the illusion of motion where there is no real motion, causing a mismatch between what they see and what the brain expects to see. Another theory is that the technology is not accurately simulating reality, that the latency is too high, the FOV is the wrong shape or size, etc. Depending on the individual threshold of the user for these discrepancies, consequences can range from disorientation, headache, discomfort to stomach awareness, drowsiness, nausea and vomiting. Virtual reality sickness can be a major issue preventing users from enjoying their experience and, because of this, developers and engineers are always keen to reduce inaccuracies and eliminate errors by devising ingenious software solutions as well as constantly improving VR technology.
