Space headache on Earth: Head-down-tilted bed rest studies simulating outer-space microgravity

BackgroundHeadache is a common symptom during space travel, both isolated and as part of space motion syndrome. Head-down-tilted bed rest (HDTBR) studies are used to simulate outer space microgravity on Earth, and allow countermeasure interventions such as artificial gravity and training protocols, aimed at restoring microgravity-induced physiological changes.ObjectivesThe objectives of this article are to assess headache incidence and characteristics during HDTBR, and to evaluate the effects of countermeasures.MethodsIn a randomized cross-over design by the European Space Agency (ESA), 22 healthy male subjects, without primary headache history, underwent three periods of –6-degree HDTBR. In two of these episodes countermeasure protocols were added, with either centrifugation or aerobic exercise training protocols. Headache occurrence and characteristics were daily assessed using a specially designed questionnaire.ResultsIn total 14/22 (63.6%) subjects reported a headache during ≥1 of the three HDTBR peri...