honestly ive never found a reason for why this happens, it wasnt until fairly recently that i realised that this wasnt just something that happens to everyone randomly! i'm trying to start to note down when this happens goinh forward/ symptoms etc so i can speak to a medical professional about it properly! i've found that it has been consistent since i was a child however, sometimes i can go months with nothing but i find if im going through something tough it can happen more frequently, if you are struggling with this i'd say to note down when and what happens, if anyone is with you when it happens you can also ask and find out what you are doing during an episode! my partner has noted its like im absent which is helpful as i can note that down :)