MH and FB conceived of the bedrest and caloric restriction design. Together with FB and MH, JP participated in the design, coordination, and execution of autonomic testing including experimental stressors and measurements. JF helped with data collection and analyzed the data. MH, FB, and JP contributed to the interpretation of data. JF and JP drafted the manuscript, and FB and MH helped to revise the manuscript. All authors have read and approved the final manuscript.