The present disclosure pertains to a system (10) configured to determine spectral boundaries (216, 218) for sleep stage classification in a subject (12). The spectral boundaries may be customized and used for sleep stage classification in an individual subject. Spectral boundaries determined by the system that are customized for the subject may facilitate sleep stage classification with higher accuracy relative to classifications made based on static, fixed spectral boundaries that are not unique to the subject. In some implementations, the system comprises one or more of a sensor (16), a processor (20), electronic storage (22), a user interface (24), and/or other components.