A user breeds a virtual life form by practicing good sleep habits and stays motivated toward practicing good sleep habits while enjoying breeding the virtual life form. A game server manages progress of a breeding game of a virtual life form, the game server including circuitry configured to acquire sleep data that at least includes a sleep pattern indicating a bedtime and a wake-up time of a user; store the acquired sleep data as a sleep history; and update the breeding game based on the sleep pattern in the sleep history.