We discuss evidence from anesthesia, sleep, and mind-wandering studies, demonstrating the frequent detachment of consciousness from external sensory inputs, resulting in states of sensory disconnection. The challenge of behaviorally distinguishing between conscious states with sensory perception (connected consciousness [CC]) and those without it (disconnected consciousness [DC]) is examined in light of current methods for assessing consciousness. We evaluate the effectiveness of objective measures and behavioral responsiveness versus subjective measures in differentiating between CC and DC states during sleep and anesthesia. We conclude that the most effective approach to study sensory disconnection in these states is to serially awaken participants during the same sleep stage or at similar anesthetic concentrations after sensory stimulation, while neuroimaging data is recorded. Upon awakening, subjective reports on consciousness and sensory perception are collected to identify CC and DC states. This methodology allows for a within-state examination of the neural signatures of sensory disconnection, minimizing biases from between-state comparisons.