<s>[INST] Everytime I stand up, either I was laying down or sitting down, I get really lightheaded, and my vision goes black. I have to lean against the wall till it passes. It happens ALL THE TIME. It doesn t matter if I get up really slowly or not, it happens. I ll even sit for awhile before I get up to try to prevent it and I ll get up ridiculously slowly but it still happens. This has been going on for about 2-3 months now, every single day. Sometimes when I m laying down it ll happen too, I m just lying there and all of a sudden I m really dizzy. Also it doesn t matter how much sleep I get, I m tired all the time. Im a 23 year old female, I work out regularly, I have struggled with depression and anxiety in the past, but other then that I m pretty much healthy. [/INST] Your symptoms suggest diagnosis of postural hypotension leading to presyncopal attacks. This occurs due to some autonomic dysfunction. You need to get assessment for autonomic functions, blood sugar, ECG, supine and standing blood pressure for postural hypotension.  In my opinion the definitive diagnosis will come after these investigations. For some relief you can increase salt and water intake and wear compression stockings in leg. Hope you recover early. Good luck. </s>