A sleep assistance apparatus, comprising: a stimulation generation unit comprising a plurality of actuators configured to generate stimulation, a user being capable of receiving the stimulation, wherein each of the plurality of actuators comprises a holder having at a holder first end portion an opening portion configured to slidably receive a slider in a length line direction, and at a holder second end portion opposite to the first end portion in the length line direction a pair of electrode units provided on the surface of the holder, a shape-memory alloy wire having central portion fixedly connected to the slider, and shape-memory wire end portions bonded to the pair of electrode units, and an elastic plate having an elastic plate first end portion that is fixed to the slider, and an elastic plate second end portion that is fixed to the holder second end portion of the holder, wherein the slider is configured to slide by a movement of a contraction of the shape-memory alloy wire in the length line direction when being energized by a current flowing through the shape-memory alloy wire via the pair of electrode units, thereby elastically deforming the elastic plate by decreasing the distance between the elastic plate first end portion and the elastic plate second end portion and generating displacement of the elastic plate in a direction perpendicular to the sliding surface of the slider; a detection unit configured to detect biological information of the user; and a control unit configured to decide stimulation on the basis of the detected biological information and depending on the stage of the user's sleep process and cause the stimulation generation unit to generate the decided stimulation, wherein the control unit is further configured to cause the stimulation generation unit to generate a plurality of kinds of stimulation in order, evaluate the detected biological information every time the stimulation is generated, and determine the stimulation for sleep introduction. a stimulation generation unit comprising a plurality of actuators configured to generate stimulation, a user being capable of receiving the stimulation, wherein each of the plurality of actuators comprises a holder having at a holder first end portion an opening portion configured to slidably receive a slider in a length line direction, and at a holder second end portion opposite to the first end portion in the length line direction a pair of electrode units provided on the surface of the holder, a shape-memory alloy wire having central portion fixedly connected to the slider, and shape-memory wire end portions bonded to the pair of electrode units, and an elastic plate having an elastic plate first end portion that is fixed to the slider, and an elastic plate second end portion that is fixed to the holder second end portion of the holder, wherein the slider is configured to slide by a movement of a contraction of the shape-memory alloy wire in the length line direction when being energized by a current flowing through the shape-memory alloy wire via the pair of electrode units, thereby elastically deforming the elastic plate by decreasing the distance between the elastic plate first end portion and the elastic plate second end portion and generating displacement of the elastic plate in a direction perpendicular to the sliding surface of the slider; a holder having at a holder first end portion an opening portion configured to slidably receive a slider in a length line direction, and at a holder second end portion opposite to the first end portion in the length line direction a pair of electrode units provided on the surface of the holder, a shape-memory alloy wire having central portion fixedly connected to the slider, and shape-memory wire end portions bonded to the pair of electrode units, and an elastic plate having an elastic plate first end portion that is fixed to the slider, and an elastic plate second end portion that is fixed to the holder second end portion of the holder, wherein the slider is configured to slide by a movement of a contraction of the shape-memory alloy wire in the length line direction when being energized by a current flowing through the shape-memory alloy wire via the pair of electrode units, thereby elastically deforming the elastic plate by decreasing the distance between the elastic plate first end portion and the elastic plate second end portion and generating displacement of the elastic plate in a direction perpendicular to the sliding surface of the slider; a detection unit configured to detect biological information of the user; and a control unit configured to decide stimulation on the basis of the detected biological information and depending on the stage of the user's sleep process and cause the stimulation generation unit to generate the decided stimulation, wherein the control unit is further configured to cause the stimulation generation unit to generate a plurality of kinds of stimulation in order, evaluate the detected biological information every time the stimulation is generated, and determine the stimulation for sleep introduction.