The present specification relates to a method for transmitting signals by a station (STA) which operates in a wireless LAN system. Here, the method for transmitting signals by a station can comprise: a step of receiving a first frame for converting a power saving (PS) mode, from an access point (AP) station, to an awake mode; and a step of transmitting a second frame for informing the awake mode of the station in response to the first frame. Here, the second frame can be a null data packet (NDP) frame.