Researchers propose brainspan as a novel metric measuring the duration of life with sufficient neural network efficiency to maintain autonomy, adaptive capacity, and coherent physiological regulation. This framework encompasses cognitive, autonomic, sleep, emotional, and behavioral networks as integrated systems rather than isolated functions. The concept addresses a critical gap in longevity medicine where extended lifespans often coincide with prolonged cognitive decline and dependency. Unlike healthspan, which focuses broadly on disease-free years, brainspan specifically targets neural efficiency as the cornerstone of meaningful aging. This framework could revolutionize how we approach cognitive preservation, shifting emphasis from treating dementia to maintaining neural network integrity throughout life. The integrated systems approach recognizes that cognitive decline rarely occurs in isolation but affects sleep quality, emotional regulation, and autonomic function simultaneously. For aging adults, this perspective suggests that interventions targeting multiple brain networks concurrently may prove more effective than addressing cognitive domains separately. The framework's emphasis on preserving independence and functional agency aligns with patient priorities for aging well, potentially guiding more targeted therapeutic strategies and lifestyle interventions in longevity medicine.