A method for predicting an arousal level used by a computer of an arousal level prediction apparatus that predicts an arousal level of a user includes obtaining current biological information regarding the user detected by a first sensor, calculating a current arousal level of the user on the basis of the current biological information, obtaining current environment information indicating a current environment around the user detected by a second sensor, predicting a future arousal level, which is an arousal level a certain period of time later, on the basis of the current arousal level and the current environment information, and (i) issuing a notification to the user or (ii) controlling another device, on the basis of the future arousal level.