> > I had been awake for a few minutes, so I got up to go get the bread out, and was struck with lightheadedness and immediately collapsed.
> > Anyway, I'm posting here to find out if anyone here has any experience with this sort of thing. Is this relatively common? Was it probably just caused by my getting up to quickly after having lain down for four hours? Or should I be worried about this?
> >
> > Don "Not too worried. But kind of worried. If that makes sense." Monkey
>
> I don't know about anyone else, but that happens to me all the time. Nearly every time I rise from a prone position, I get that weird blacking-out feeling. Sometimes it's worse than others. I called my mother the first time it happened, and she said it was a deficiency of potassium. She told me to eat a banana. ...
>

You're both right -- standing up fairly rapidly from prone position is the problem. The dizziness, faintness, and seeing black spots are common enough symptoms, and I think I don't know anyone who *hasn't* experienced this. The condition is called postural hypotension (orthostatic, or transient low blood pressure). It's due to a temporary drop in blood pressure after an abrupt change in body position from the resting state... Since it always takes a moment for your heart and venoconstrictors to compensate for the blood draining out of your head as you stand up, in that time you might lose consciousness and wake up to find yourself on the floor.

So if this hypotension condition happens but rarely, all that is required to resolve it is to get up, slowly, in stages (i.e. slide legs out of bed first; then sit up slowly.) But if the condition is chronic, well... then something else which is physical is involved; possibly it could be a conflict with medications taken for other disorders. Best go see a physician, in any case.

Wolfspirit