This study investigates the relationship between gravity and the angle of repose (AoR) in granular materials, a key parameter in the geomorphology of planets and industrial applications. Avalanches of glass beads, volcanic sand, river sand, and their mixtures were tested in Hele-Shaw cells, in various hypergravity environments (1g to 20g). A numerical method was developed to measure the AoR, validated for experiments with 3% accuracy. The AoR displays cyclic and stable AoR trends, influenced by gravity, avalanching regimes, and material properties. This was revealed by introducing the novel "heartbeat" graphs. Results suggest a "V-shaped" AoR curve across gravity levels: high in low hypogravity, decreasing near 1g, increasing from 1g to 3g, and stabilising beyond 5g. This study highlights the Froude number as a critical unifying parameter for reconciling findings across the literature.