Interesting. When my hypovolemia was at its most severe, due to it (not the cause of it) ended up having too sleep (or even when laying at times) with my head and a bit of my upper body hanging off the bed (it was the only way I could help the dizziness of not having enough blood to my head).. I also had to raise the foot end of the bed. Over time I improved to the point where I didnt need to do that any more to sleep or to cut back on symptoms. (I still do thou have hypovolemia issues). So if anyone is having to do the same.. dont be put off by those findings as I was doing that and improved. (I dont thou recommend doing this unless its a case of needing to do it).