The present invention is related to a sleep state detection method, apparatus and system. The method comprises: upon detecting that a current state of a user satisfies a preset sleep condition, sending a state checking request to a terminal, so that the terminal checks sensor data and/or an operation event of a preset application on the terminal according to the state checking request, wherein the terminal is bound to the smart wearable device receiving state information, which is fed back by the terminal based on a result of the checking and determining whether the user enters a sleep state, based on the state information. With this solution, the smart wearable device determines whether the user enters the sleep state with the assistance of the terminal, thereby preventing the smart wearable device from miscalculating the users sleep duration and even misjudging that a sleep quality problem occurs, ensuring the accuracy of calculating the users sleep duration and improving the user experience.