We all know that adequate sleep is a necessity for good health and that exposure to chronic abnormal sleep cycles, such as that experienced by shift workers, can lead to a variety of chronic diseases like diabetes and heart disease. Now, consider the challenges that space travel poses for maintaining normal sleep. For example, astronauts on the International Space Station, instead of experiencing a 24-hour solar day, complete one solar cycle every 90 minutes! Such an unnatural environment can potentially wreak havoc on a mammalian circadian system that has evolved over millions of years to synchronize with the 24-hour rotation of the earth.
Oregon Institute of Occupational Health Sciences Director Steve Shea has been investigating how the heart and vascular system responds to disrupted sleep in the space environment. Dr. Shea has a research grant funded by NASA entitled: Identification of Cardiometabolic Vulnerabilities Caused by Effects of Synergistic Stressors that are Commonly Encountered during Space Missions. The major goal of this grant is to assess the cardiovascular system responses to exercise, postural tilt and mental stress during combined sleep loss and circadian misalignment, as occurs with space flight.
Recently, Dr. Shea participated in a workshop sponsored jointly by the National Space Biomedical Research Institute (NSBRI) and the National Aeronautics and Space Administration (NASA) titled Sleep on Earth and in Space: Risk Factors, Health & Performance Outcomes, and Countermeasures, Sept 29-30, in Houston, Texas. The workshop goals were to: review state-of-the-art knowledge of the effects of environmental factors on sleep; review state-of-the-art knowledge of the effects of sleep or insufficient sleep on multiple physiological and psychological functions; and encourage inter-disciplinary work, including countermeasure development, on these topics.
This type of workshop will lead to new research assessing the health impact of spaceflight on astronauts, including during possible long-term missions to Mars and back, which would take over a year. Scientists want to answer the question: if achieved sleep falls below desired levels, or if circadian misalignment occurs for prolonged periods, what mitigating strategies and countermeasures for health and performance outcomes can be used?