Background:Spaceflight studies have demonstrated that adaptation to increased gravitational stress after prolonged microgravity includes sympathetic activation, water retention, and arterial pressure increase, i.e. is very similar to essential hypertension, which looks like an advanced stage of adaptation to a further increase in gravitational stress.Material/Methods: Theoretical analysis and literature review were performed to develop an hypothesis of essential hypertension as adaptation to increased gravitational stress associated with prolonged sitting.Results: Gravitation shifts blood downwards, and gravitational stress (GS) on the cardiovascular system in an upright position may be defined as the amount of work necessary to return the blood upwards and maintain adequate upper-body circulation calculated as the product of the gravitational potential (Ugr=g*h) and the mass of blood moved: GS =Ugr*Mshift. In a complex vascular network, this blood shift is actually a function of time, estimated in a first approximation as Mshift(t)=(Ugr*t)/Rd (Rd: the resistance to downward blood flow). Thus, gravitational stress is proportional to the time spent upright GS=Ugr*Mshift(t)=(Ugr2*t)/Rd=(g2*h2*t)/Rd. From this analysis, regular, prolonged sitting typical of modern life should cause a significant increase in gravitational stress on the cardiovascular system, requiring advanced antigravitational response with sympathetic hyperactivity, vasoconstriction, volume overload, and arterial hypertension. The hypertensive effect of prolonged sitting has been demonstrated in clinical studies.Conclusions: Essential hypertension may be explained as adaptation to increased gravitational stress caused by regular, prolonged sitting. This gravitational hypothesis of essential hypertension, supported by clinical data, offers a way to its complete healing through elimination of the primary factor of prolonged sitting.

Keywords: Adaptation, Physiological - physiology, Genetic Predisposition to Disease, Gravitation, Hypertension - genetics, Hypertension - physiopathology, Hypertension - prevention & control, Hypertension - therapy, Life Style, Stress - physiopathology, Adaptation, Physiological - physiology, Genetic Predisposition to Disease, Gravitation, Hypertension - therapy, Life Style, Stress, Physiological - physiopathology