Embodiments of a method and/or system for characterizing one or more sleep-related conditions can include determining a microorganism dataset associated with a set of subjects; and/or performing a characterization process associated with the one or more sleep-related conditions, based on the microorganism dataset, where performing the characterization process can additionally or alternatively include performing a sleep-related characterization process for the one or more sleep-related conditions, and/or determining one or more therapies S140.