Abstract: A bed has a mattress. One or more sensors are configured to sense one or more physical phenomena of a sleeper on the bed and generate data signals based on the sensed physical phenomena; and send, to a computing system, the data signals. A computing system comprising one or more processors and computer memory. The computing system is configured to: receive the data signals; generate, from data signals of a sleep-session of the sleeper, a feature vector of features, each feature having a feature value that represents one of the physical phenomena; and classify the sleeper into a classified physical state for the sleep session based on the feature vector.