The following periods are of very high importance for science: - from the beginning of lunch until 30 minutes after the end of lunch - from the beginning of dinner until 30 minutes after the end of dinner - from one hour before the cosmonaut goes to sleep until a minimum of one hour after the transition awake-sleep. The recording could last until the end of the sleep phase if the battery capacity allows it. - from wake up until one hour after wake up.
The cosmonaut shall do his normal work during the day of the experiment. The in-flight part of the experiment was conducted in the Russian module of ISS, and was repeated twice at the beginning and at the end of the flight. The overall experiment has two preflight baseline data collection sessions. The postflight part of the experiment recorded return to normal gravity circumstances. This part was also performed twice.
This study has shown that astronauts on short-lasting space flight may be subject to strong psychological stimuli. In particular ‘official’ moments like press-conferences can induce surges of blood pressure and heart rate. The authors recorded in-flight 24-hour profiles of BP and HR in 2 ESA-astronauts by automatic upper arm cuff measurements; in one astronaut this was combined with continuous finger blood pressure monitoring, which allows additional estimation of cardiac output and vascular resistance. The initial hypothesis was that spaceflight would show the same day/night changes as had been observed earlier in ground based (Head Down Tilted – HDT) simulation studies. However, unlike the simulations, BP and HR were not very much changed in-flight from preflight. Only daytime diastolic pressures (both subjects) and nighttime HR (for one subject) were significantly lower in-flight than preflight. Actual space flight did not confirm the earlier HDT findings for BP-levels and for daytime to nighttime changes. Daytime BP-levels were definitely higher than was expected; strikingly, BP- and HR-surges during the working days in space were often related to stressful moments like live media events, but were not restricted to these moments. The authors hypothesize that the busy work schedule of short-stay astronauts adds to the general level of arousal that is apparent from the measurements. This study shows that extensive in-flight cardiovascular measurements are feasible, even in busy astronauts, while they are performing their normal duties. From these observations, researchers have learned to take the psychological aspects of spaceflight more into account when judging the adaptation to microgravity. (Karemaker et al., 2009).