Rice's Science Journal says we experience high G-force in our everyday life, including such actions as sneezing. Grayouts or blackouts on roller coasters are usually caused by not having enough to eat or being dehydrated. It can also be caused by hypoxia or low blood oxygen heat stress, fatigue and consecutive rides.

Yes, it is physiologically possible to lose consciousness on a roller coaster, a phenomenon often referred to as a "G-LOC" (G-force induced Loss Of Consciousness). This typically occurs during high-speed maneuvers that pull intense positive G-forces, which pull blood away from the head and toward the lower body. When the brain is momentarily deprived of oxygenated blood, riders may experience a "gray-out," "black-out," or a brief period of fainting. Most modern 2026 coasters are engineered to keep these forces within safe human limits (usually below 5G for brief durations), but factors like dehydration, low blood pressure, or a rider's physical positioning can increase the risk. While these "syncopal episodes" are usually very brief—lasting only a few seconds—and riders typically wake up as soon as the G-forces level out, it is a significant strain on the cardiovascular system. It is a peer-to-peer recommendation to stay well-hydrated and avoid riding on an empty stomach to help maintain the blood pressure necessary to resist these forces.