An analysis system and method are provided for analyzing physical information and acquiring biological data of a user from a biological data acquisition sensor. The exemplary analysis system includes a circadian rhythm calculator that calculates an average circadian rhythm of the user; an autonomic nerve analyzer that performs autonomic nerve analysis based on a variation in the biological data; and a physical information analyzer that weights an autonomic nerve analysis result analyzed by the autonomic nerve analyzer with a weighting coefficient set based on a measurement time at which the biological data of the user is acquired and a cycle of the average circadian rhythm. The physical information analyzer also estimates a change in a circadian rhythm with respect to the average circadian rhythm based on the weighted autonomic nerve analysis result.