A determination system includes an obtainer, a determiner, and an outputter. The obtainer obtains a result of detection by a first sensor which detects a body movement of a body part of a user exposed from a covering, and a result of detection by a second sensor which detects a body movement of the user. The determiner determines a sleep state of the user, based on the result of detection by the first sensor and the result of detection by the second sensor, which are obtained by the obtainer, the sleep state including a state of the covering. The outputter outputs information based on a result of determination by the determiner.