# Rules of Heliogeomagnetics Diversely Coordinating Biological Rhythms and Promoting Human Health
## 4 Discussion
### Rules of Procedure in Exploring Heliogeomagnetic Effects on Human Physiology  
The magnetosphere is a vast cavity in which the Earth resides. It stems from the interaction between the geomagnetic field and the solar wind (a gas of charged particles flowing from the Sun) [29, 111]. Life on Earth is protected by the atmosphere and the magnetic field. The Earth's magnetic field also protects the ISS from the space environment [111]. Biological effects thus result from exposure to weak geomagnetic fields from Earth and space [112, 113, 114, 33, 46]. As a function of solar cycle number, we found different HRV responses associated with geomagnetic disturbances: Our previous 2009-2016 studies (during solar cycle 24) on the ISS in space, the HRV (including TF, ULF, VLF, and LF components) response increased in seven clinically healthy astronauts [18; 19]. Contrary to our 1998-2000 subarctic studies (solar cycle 23), HRV indices were suppressed in 19 clinically healthy individuals in response to magnetic storms, which involved larger magnetic disturbances than those observed in space [70; 71; 72]. HRV endpoints are hence affected by magnetic fluctuations in the magnetosphere, which enhance cardiovascular circadian rhythms, as shown herein. These effects bear on human health, well-being, and psychological resilience. Results from our studies on the ISS further suggest a possible anti-aging effect, probably mediated by the brain default mode network (DMN), in a light-dependent manner and/or with help from biological clocks [18; 19; 20]. This kind of information might lead to the formulation of new hypotheses and account for unanticipated results when accounting for the effects of magnetic storms that have an effect on the heart and brain, as we now learned. Concern for magnetic fluctuations entered programs on scientific chronobioethics for human health: the resonance of biological rhythms, brain plasticity, and psychological resilience. Further work on underlying molecular mechanisms, however, is warranted. Several procedural rules in exploring chronobioethics are proposed:  
1. The atmosphere and the magnetic field provide protection on Earth [111]. Geomagnetic fluctuations in the magnetosphere significantly affect humans not only on Earth but also in space. 2. Humans living at higher geomagnetic latitudes are particularly affected, as geomagnetic disturbances are stronger in arctic areas [55; 71]. 3. Effects of geomagnetic disturbances on human physiology are nonlinear and display hormetic responses [72], perhaps understood as part of a broader bell-shaped dose-response curve [85]. Windowed responses appear only in a certain range of doses, which may differ among individuals and change depending on circumstances. They account for the lack of response outside, contrasting with a strong response inside these 'windows' [27; 28; 29; 33; 55; 71; 85; 87]. Extremely high as well as extremely low geomagnetic activity seem to suppress BP or HRV variability and have adverse health effects [55]. 4. Decreases in HRV linked to geomagnetic storms, occurring more frequently when solar activity is high, reportedly increase cardiovascular risk in susceptible individuals. BP variability, on the other hand, is larger during solar minima and ascending solar cycle phases than during solar maxima, but storms during solar minima are more intense than those during solar maxima, perhaps accounting for changes in BP behavior along the course of the solar cycle [33; 42]. 5. Effects of magnetic fluctuations on the activity of the brain's DMN are modulated by light and/or the circadian clock. Transcranial magnetic stimulation seemed to create a shift in the relationship between the medial prefrontal cortex and the dorsolateral prefrontal cortex, two nodes in the DMN [18; 19; 20; 115]. 6. Geomagnetic stimulation at night improved sleep quality and induced slow-wave deep sleep not only on Earth but also in space. Geomagnetic disturbances also affect psychophysical processes.