Chronic head-down-tilt sleeping as physiological regulator of bone remodelling during diminished muscular activity in humans.

Objectives: Head-down-tilt (HDT) sleeping with periodic fluid redistribution (PFR) assumes a significant importance by the possibility of regulating bone remodelling. We hypothesized that HDT sleeping with chronic PFR which expands fluid volume would contribute to and/or increase bone formation. Therefore, we studied the potential benefits of osteogenesis with HDT sleeping of chronic PFR during diminished muscular activity (hypokinesia; HK).