Period panties should be changed every 4 to 6 hours. This depends on the flow and the other products you’re using along with the menstrual panties. If you have ditched pads and tampons and are only using menstrual panties, you should change them as soon as it feels uncomfortable or too wet. This is advisable, especially on days with flow. These panties are a better option for days with mild spotting. If you are worried about leaking pads while sleeping, you can wear a period panty for a more comfortable and tension-free night of sleep.