Hi Sandra
When we sleep flat the body stores salts because they do not migrate to the kidneys as efficiently as when we are sleeping inclined. When salts are concentrated by evaporation as we exhale and from continuous loss of moisture from the skin, and eyes, gravity dictates that these denser fluids must move towards the ground. If we are sleeping on an angle, the salts can flow down the main artery for example and into the kidneys, where they are filtered more efficiently, flowing on into the bladder, where eventually excreted in the urine. The salts and minerals can be found in lime scale deposits in urinals. So there is no doubt that these dissolved minerals are excreted from the bladder. As I stated before, a simple head down tilt proved the link when my wife’s urine and mine gave us a near water density reading and the opposite occurred when we slept head up or Inclined.
When a person avoids sleeping flat, the circulation is enhanced so that these stored minerals move towards the renal filtration. As they enter the circulation, they introduce an increase in positive pressure to the artery, which is balanced by an increase in tension in the blood within the venous return. Again this tension is obvious given that varicose veins are becoming less obvious and over time have returned to normal looking veins.
In your particular case, though this is merely conjecture now as I do not have any means of testing this, there could be a restricted / kinked venous return, this would mean that the heart is pumping against a constricted vein and because the blood flows out of the heart under an enhanced positive pressure it could lead to a gradual backing up of blood causing an overall increase in blood pressure.
The following paper points out important changes in venous return flow and posture, though does not consider any possible motivating force for this change in flow.
In the vast majority of cases high blood pressure drops and become normal and low blood pressure is also corrected, which I could not understand, but now thanks to Zamboni and his colleagues we are beginning to understand the problems with circulation in ms more.
The difference in venous outflow alters from horizontal to standing. The question is what is happening on an inclined bed and at what angle does it alter?
Human cerebral venous outflow pathway depends on posture and central venous pressure
Author: Andrew K Fletcher
•12:41 PM
J Physiol. 2004 Oct 1;560(Pt 1):317-27. Epub 2004 Jul 29.
Human cerebral venous outflow pathway depends on posture and central venous pressure.
Gisolf J, van Lieshout JJ, van Heusden K, Pott F, Stok WJ, Karemaker JM.
Department of Physiology, Room M01-07, Academic Medical Center, University of Amsterdam, PO Box 22700, 1100 DE Amsterdam, the Netherlands.
j.gisolf@amc.uva.nl.
Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans the positioning of these veins above heart level causes them to collapse. An alternative cerebral outflow pathway is the vertebral venous plexus. We set out to determine the effect of posture and central venous pressure (CVP) on the distribution of cerebral outflow over the internal jugular veins and the vertebral plexus, using a mathematical model. Input to the model was a data set of beat-to-beat cerebral blood flow velocity and CVP measurements in 10 healthy subjects, during baseline rest and a Valsalva manoeuvre in the supine and standing position. The model, consisting of 2 jugular veins, each a chain of 10 units containing nonlinear resistances and capacitors, and a vertebral plexus containing a resistance, showed blood flow mainly through the internal jugular veins in the supine position, but mainly through the vertebral plexus in the upright position. A Valsalva manoeuvre while standing completely re-opened the jugular veins. Results of ultrasound imaging of the right internal jugular vein cross-sectional area at the level of the laryngeal prominence in six healthy subjects, before and during a Valsalva manoeuvre in both body positions, correlate highly with model simulation of the jugular cross-sectional area (R(2) = 0.97). The results suggest that the cerebral venous flow distribution depends on posture and CVP: in supine humans the internal jugular veins are the primary pathway. The internal jugular veins are collapsed in the standing position and blood is shunted to an alternative venous pathway, but a marked increase in CVP while standing completely re-opens the jugular veins.
