What happens to the pressure of blood?

Arteries and veins have different structures, diameters and elasticity to deal with the impact of gravity on the relative height of a body the blood must flow through. This creates different relative pressures between arteries & veins.

Without regulated blood vessel flow the blood would drop with gravity and pool if not contained and it would stay pooled if back flow was not prevented on the return against gravity.

Arteries withstand higher blood pressure with thick elastic walls that help smooth out fluctuations due to heart beats and muscles help regulate flow.

Elastic arteries conduct the flow from the heart branching to more muscular vessels with smaller diameters that distribute the flow to organs or branching to arterioles & capillary beds.

The regulated aperture helps resist gravity but can be adjusted by the smooth muscles in the vessel walls with demand. blood volume changes or viscosity changes.

http://classes.midlandstech.edu/carterp/Courses/bi...

Elasticity helps accommodate changes in blood volume and keep a constant blood pressure. Stiffened inelastic arteries make the heart work harder.

Veins have oneway valves that prevent backflow with gravity. Veins have thin walls for a larger inner diameter to permit a greater freedom of forward flow and a larger volume than arteries. Despite more blood and moving against gravity they have a lower blood pressure with the larger opening due to thin walls. Veins store some 60 – 70% of the body’s blood giving a buffer against blood loss in an accident.

http://faculty.stcc.edu/AandP/AP/AP2pages/Units18t...

Assuming this is neither medication induces nor secondary to any specific pathology your stroke and heart attack risks drop BELOW normal. The down side may be postural dizziness.