Do geomagnetic disturbances of solar origin affect arterial blood pressure?

Biological Effects of Magnetic Storms and ELF Magnetic Fields

Magnetic fields are a constant and essential part of our environment. The main components of ambient magnetic fields are the constant part of the geomagnetic field, its fluctuations caused by magnetic storms, and man-made magnetic fields. These fields refer to extremely-low-frequency (<1 kHz) magnetic fields (ELF-MFs). Since the 1980s, a huge amount of data has been accumulated on the biological effects of magnetic fields, in particular ELF-MFs. However, a unified picture of the patterns of action of magnetic fields has not been formed. Even though a unified mechanism has not yet been generally accepted, several theories have been proposed. In this review, we attempted to take a new approach to analyzing the quantitative data on the effects of ELF-MFs to identify new potential areas for research. This review provides general descriptions of the main effects of magnetic storms and anthropogenic fields on living organisms (molecular-cellular level and whole organism) and a brief description of the main mechanisms of magnetic field effects on living organisms. This review may be of interest to specialists in the fields of biology, physics, medicine, and other interdisciplinary areas.

Linkages Between Geomagnetic Activity and Blood Pressure

This review aims to critically examine and present evidence for and against potential linkages between geomagnetic activity and its effects on blood pressure (BP). Four databases were searched for peer-reviewed papers written in English: PubMed, Web of Science, EMBASE, and Biomedical Reference Collection. Retrieved titles were first screened for potential relevance followed by an abstract review for further clarifications if warranted. The preponderance of the reported evidence is consistent with the concept that space weather and related events that cause sufficiently large changes in the geomagnetic field (GMF) can impact BP. The associated BP change in most but not all cases is one in which both systolic blood pressure (SBP) and diastolic blood pressure increase, with SBP appearing to be more consistently involved. The magnitude of the reported BP increase ranges from about 3 to 8 mmHg depending on the intensity of the geomagnetic activity. The initiation of these BP changes has been variably reported to occur shortly before the GMF change or in synchrony with the abrupt change in the GMF. Such GMF-linked BP changes are not present in all persons and there appears to be increased sensitivity in women and in persons with co-existing hypertension. The utility of these findings in assessing or treating persons with known or suspected hypertension remains to be determined via future research. Further, research directed at determining the factors that determine responders from non-responders to GMF changes is warranted.

The effect of electromagnetic field on sleep of patients with nocturia

INTRODUCTION

Accumulated studies revealed that electromagnetic field can affect human brain and sleep. We explored the effectiveness of electromagnetic field [Schumann resonance (SR)] on nocturia symptoms, quality of life, and sleep in patients with nocturia.

METHODS

This is a randomized, open-label, and active-controlled study, in which 35 participants were randomized into 2 groups. Group A received oxybutynin and the SR device for 12 weeks, while the active-control group received only the medication. We followed these patients every 4 weeks with a number of questionnaires, including the Pittsburgh sleep quality index (PSQI) and Epworth sleepiness scale (ESS) for sleep, the American Urological Association Symptom Score (AUASS) for nocturia symptoms, and the Nocturia-Quality-of-Life-questionnaire (N-QOL) for quality of life. Descriptive statistics, pair t-tests, Chi-squared tests, and repeated measures were applied for data analysis.

RESULTS

No significant difference was found in the demographic data between the 2 groups. The AUASS, N-QOL, PSQI, and ESS total scores were significantly improved in the SR-sleep-device group (P < .001, P = .005, P < .001, P = .001) after treatment, but no significant change was found in the active-control group. Several variables of AUASS in the SR-sleep-device group were significantly improved, especially streaming and sleeping (both P = .001), and subjective sleep quality and sleep efficiency also demonstrated significant improvement (both P < .001).

CONCLUSIONS

Our study revealed that electromagnetic field (SR) as an add-on can improve not only sleep and quality of life but also nocturia symptoms in patients with nocturia. These findings suggest that SR can be effective for sleep disturbance secondary to physical disease, which can be a new application of the electromagnetic field.

The Subjective and Objective Improvement of Non-Invasive Treatment of Schumann Resonance in Insomnia-A Randomized and Double-Blinded Study

PURPOSE

Accumulated studies revealed that electromagnetic field can affect human brain and sleep, and the extremely low-frequency electromagnetic field, Schumann resonance, may have the potential to reduce insomnia symptoms. The purpose of this study was to investigate the responses of patients with insomnia to a non-invasive treatment, Schumann resonance (SR), and to evaluate its effectiveness by subjective and objective sleep assessments.

PATIENTS AND METHODS

We adopted a double-blinded and randomized design and 40 participants (70% female; 50.00 ± 13.38 year) with insomnia completed the entire study. These participants were divided into the SR-sleep-device group and the placebo-device group and were followed up for four weeks. The study used polysomnography (PSG) to measure objective sleep and used sleep diaries, Pittsburgh Sleep Quality Inventory (PSQI), Epworth Sleepiness Scale (ESS), and visual analogy of sleep satisfaction to measure subjective sleep. The 36-Item Short-Form Health Survey (SF-36) was used to evaluate quality of life. Chi-square test, Mann-Whitney U-test, and Wilcoxon test were used to analyze the data.

RESULTS

About 70% of the subjects were women, with an average age of 50±13.38 years and an average history of insomnia of 9.68±8.86 years. We found that in the SR-sleep-device group, objective sleep measurements (sleep-onset-latency, SOL, and total-sleep-time, TST) and subjective sleep questionnaires (SOL, TST, sleep-efficiency, sleep-quality, daytime-sleepiness, and sleep-satisfaction) were significantly improved after using the SR-sleep-device; in the placebo-device group, only such subjective sleep improvements as PSQI and sleep-satisfaction were observed.

CONCLUSION

This study demonstrates that the SR-sleep-device can reduce the insomnia symptoms through both objective and subjective tests, with minimal adverse effects. Future studies can explore the possible mechanism of SR and health effects and, with a longer tracking time, verify the effectiveness and side effects.

Solar Activity Is Associated With Diastolic and Systolic Blood Pressure in Elderly Adults

Background

Since solar activity and related geomagnetic disturbances modulate autonomic nervous system activity, we hypothesized that these events would be associated with blood pressure (BP).

Methods and Results

We studied 675 elderly men from the Normative Aging Study (Boston, MA) with 1949 BP measurements between 2000 and 2017. Mixed‐effects regression models were used to investigate the association of average 1‐day (ie, day of BP measurement) to 28‐day interplanetary magnetic field intensity, sunspot number, and a dichotomized measure of global geomagnetic activity (K_p index) in 4‐day increments with diastolic and systolic BP. We adjusted for meteorological conditions and other covariates associated with BP, and in additional models adjusted for ambient air pollutants (particulate matter with an aerodynamic diameter ≤2.5 µm, black carbon, and particle number) and ambient particle radioactivity. There were positive associations between interplanetary magnetic field, sunspot number, and K_p index and BP that were greatest with these exposures averaged over 16 through 28 days before BP measurement. An interquartile range increase of 16‐day interplanetary magnetic field and sunspot number and higher K_p index were associated with a 2.5 (95% CI, 1.7‒3.2), 2.8 (95% CI, 2.1‒3.4), and 1.7 (95% CI, 0.8‒2.5) mm Hg increase, respectively, for diastolic BP as well as a 2.1 (95% CI, 0.7‒3.6), 2.7 (95% CI, 1.5‒4.0), and 0.4 (95% CI, −1.2 to 2.1) mm Hg increase, respectively, for systolic BP. Associations remained after adjustment for ambient air pollutants and ambient particle radioactivity.

Conclusions

Solar activity and solar‐driven geomagnetic disturbances were positively associated with BP, suggesting that these natural phenomena influence BP in elderly men.

Systemic lupus Erythematosus and geomagnetic disturbances: a time series analysis

BACKGROUND

To examine the influence of solar cycle and geomagnetic effects on SLE disease activity.

METHODS

The data used for the analysis consisted of 327 observations of 27-day Physician Global Assessment (PGA) averages from January 1996 to February 2020. The considered geomagnetic indices were the AP index (a daily average level for geomagnetic activity), sunspot number index R (measure of the area of solar surface covered by spots), the F10.7 index (measure of the noise level generated by the sun at a wavelength of 10.7 cm at the earth's orbit), the AU index (upper auroral electrojet index), and high energy (> 60 Mev) proton flux events. Geomagnetic data were obtained from the Goddard Space Flight Center Space Physics Data Facility. A time series decomposition of the PGA averages was performed as the first step. The linear relationships between the PGA and the geomagnetic indices were examined using parametric statistical methods such as Pearson correlation and linear regression, while the nonlinear relationships were examined using nonparametric statistical methods such as Spearman's rho and Kernel regression.

RESULTS

After time series deconstruction of PGA averages, the seasonality explained a significant fraction of the variance of the time series (R2 = 38.7%) with one cycle completed every 16 years. The analysis of the short-term (27-day) relationships indicated that increases in geomagnetic activity Ap index (p < 0.1) and high energy proton fluxes (> 60 Mev) (p < 0.05) were associated with decreases in SLE disease activity, while increases in the sunspot number index R anticipated decreases in the SLE disease activity expressed as PGA (p < 0.05). The short-term correlations became statistically insignificant after adjusting for multiple comparisons using Bonferroni correction. The analysis of the long-term (297 day) relationships indicated stronger negative association between changes in the PGA and changes in the sunspot number index R (p < 0.01), AP index (p < 0.01), and the F10.7 index (p < 0.01). The long-term correlations remained statistically significant after adjusting for multiple comparisons using Bonferroni correction.

CONCLUSION

The seasonality of the PGA averages (one cycle every 16 years) explains a significant fraction of the variance of the time series. Geomagnetic disturbances, including the level of geomagnetic activity, sunspot numbers, and high proton flux events may influence SLE disease activity. Studies of other geographic locales are needed to validate these findings.

The Possible Effect of Space Weather Factors on Various Physiological Systems of the Human Organism

A systematic review of heliobiological studies of the last 25 years devoted to the study of the potential influence of space weather factors on human health and well-being was carried out. We proposed three criteria (coordinates), according to which the work on solar–biospheric relations was systematized: the time scale of data sampling (years, days, hours, minutes); the level of organization of the biological system under study (population, group, individual, body system); and the degree of system response (norm, adaptation, failure of adaptation (illness), disaster (death)). This systematic review demonstrates that three parameters mentioned above are closely related in the existing heliobiological studies: the larger the selected time scale, the higher the level of estimated biological system organization and the stronger the potential response degree is. The long-term studies are devoted to the possible influence of solar activity on population disasters, i.e., significant increases in morbidity and mortality. On a daily scale, a probable effect of geomagnetic storms and other space weather events on short-term local outbreaks of morbidity is shown as well as on cases of deterioration in people functional state. On an intraday scale, in the regular functioning mode, the heart and brain rhythms of healthy people turn to be synchronized with geomagnetic field variations in some frequency ranges, which apparently is the necessary organism’s existence element. The applicability of different space weather indices at different data sampling rates, the need to take into account the contribution of meteorological factors, and the prospects for an individual approach in heliobiology are discussed. The modern important results of experiments on modeling the action of magnetic storms in laboratory conditions and the substantiation of possible theoreical mechanisms are described. These results provide an experimental and theoretical basis for studies of possible connections of space weather and human health.

Effectiveness of Natural Frequency Technology® on cognition, sleep, and mood of adults with high perceived stress: A randomized, double-blind, placebo-controlled crossover study

INTRODUCTION

NexQuest Natural Frequency Technology^® (NFT^® ), intended to enhance biological function using naturally occurring frequencies, may be a nonpharmacological intervention to improve stress and health. The study purpose was to determine the effectiveness of NFT^® for improving stress, sleep quality, mood, and cognition in adults.

METHODS

Using a double-blind placebo-controlled crossover design, participants with high perceived stress (N = 42, M age = 43.8) were assessed at baseline (BL) and assigned to either the Placebo Watch (PW) or Wellness Watch (WW) condition for 2 weeks, and then 2 weeks in the alternate condition. Participants completed the following self-report surveys of Perceived Stress Scale, Pittsburgh Sleep Quality Index, Insomnia Severity Index, Food Craving Questionnaire, and Profile of Mood States, as well as the CNS Vital Signs neurocognitive test at BL and following each condition.

RESULTS

The WW condition had significant improvements in sleep duration and Complex Attention compared to the PW group. Compared to BL, both conditions had significant improvements for perceived stress, food cravings, mood, sleep quality, and several cognitive tests, p's < .05.

CONCLUSION

Despite the placebo effect, NFT^® may be a natural alterative for improving stress and health. Research is needed examining the efficacy of NFT^® in a variety of populations and environments.

The associations of geomagnetic storms, fast solar wind, and stream interaction regions with cardiovascular characteristic in patients with acute coronary syndrome

It is shown the statistical associations between space weather pattern and humans' cardiovascular system. We investigated the association between space weather events and cardiovascular characteristics of 4076 randomly selected patients with acute coronary syndrome (ACS) who were admitted for inpatient treatment in Kaunas city, Lithuania during 2000-2005. We hypothesized that days of the space weather events, 1-3 days after, and the period between two events, named as intersection days (1-3 days after the event, which coincided with 1-3 days before the event), might be associated with patients' cardiovascular characteristics. The multivariate logistic regression was applied, and the patients' risk was evaluated by odds ratio (OR), adjusting for age, sex, smoking status, the day of the week, and seasonality. During the intersection days of geomagnetic storms (GS), the risk of ACS increases in obese patients (OR=1.72, p = 0.008). The risk of ventricular fibrillation during admission was associated with stream interaction region (SIR) with a lag of 0-3 days (OR=1.44, p = 0.049) The risk of ACS in patients with chronic atrial fibrillation was associated with fast solar wind (FSW) (≥600 km/s) (lag 0-3 days, OR=1.39, p = 0.030) and with days of solar proton event (lag 0-3) going in conjunction with SIR (lag 0-3) (OR=2.06, p = 0.021). During days which were not assigned as GS with a lag of (-3 to 3) days, FSW (lag 0-3) was associated with the risk of ACS in patients with renal disease (OR=1.71, p = 0.008) and days of SIR - with the risk in patients with pulmonary disease (OR=1.53, p = 0.021). A SIR event, days between two space weather events, and FSW without GS may be associated with a risk to human health.

The influence of the North Atlantic Oscillation index on arterial blood pressure

AIM

to detect the complex association between arterial blood pressure (BP) and air temperature, atmospheric pressure, relative humidity, wind speed, and North Atlantic oscillation (NAO) indices.

METHODS

Data were obtained from the survey performed in the framework of the international Health, Alcohol and Psychosocial Factors in Eastern Europe study. The number of individuals used in the models or other analysed groups was 7077. The association between environmental variables and SBP and DBP were evaluated by applying the multiple regression analysis, adjusting for health-related and weather variables.

RESULTS

More than one-half (58.7%) of the respondents had high BP, and 39.4% of the respondents had taken drugs for high BP during the last 2 weeks. Among the respondents, the mean SBP and DBP were 141.6 ± 22.2 and 90.4 ± 12.5 mmHg, respectively. An increase in SBP was associated with the presence of a lower relative humidity, and a higher wind speed and extreme atmospheric pressure with a lag of 2 days. During the period of spring-autumn, continuous NAO indices on the same day and a positive NAO on the same and on 2 previous days were negatively associated with the SBP value. A positive NAO was associated (P = 0.001) with a decrease in SBP by 1.7 mmHg in all participants, by 2.30 mmHg in physically active participants, and by 3.62 mmHg in the elderly, as compared with a negative NAO.

CONCLUSION

These results provided new evidence that the NAO index may be affect the value of SBP and DBP in the elderly during the period of spring-autumn.

Schumann resonance and cardiovascular hospital admission in the area of Granada, Spain: An event coincidence analysis approach

The study of bio-effects of Schumann resonances is a very complex issue. There is a need to identify mechanisms and pathways that explain how Extremely Low Frequency magnetic fields affect biology or human health. This particular study tries to identify statistical associations between ELF magnetic fields in the province of Granada (Spain) and cardiovascular related hospital admission in the same province for the period April, 1st 2013 to March, 31st 2014. Research is developed under an epidemiological approach based on an Event Coincidence Analysis statistical method. Clustered events, statistically significant (ECA shuffle-surrogate test p = .01 and p < .01), were found for the minimum values of the first and the third Schuman resonances frequency on east-west and north-south directions, and for the amplitude parameter of the second resonance and the total signal energy in the north-south direction. Empirical measurements of SR parameters were recorded at the Sierra Nevada Mountain in Granada province (Spain). Results show a clear coincidence of the events for the minima amplitudes of Shuman resonances and energy in the north-south orientation and the number of the cardiovascular related hospital admissions. Further research is needed with longer temporal series and a new approach based on gender seems to be also interesting for future studies.

A simulated geomagnetic storm unsynchronizes with diurnal geomagnetic variation affecting calpain activity in roach and great pond snail

It has been suggested that geomagnetic storms could be perceived by organisms via disruption of naturally occurring diurnal geomagnetic variation. This variation, in turn, is viewed by way of a zeitgeber for biological circadian rhythms. The biological effects of a geomagnetic storm, therefore, could depend on the local time of day when its main phase occurs. We have assessed calpain activity in tissues of roach (Rutilus rutilus) and great pond snail (Limnaea stagnalis) after exposure to a simulated geomagnetic storm, reproduced at different times of day, in order to evaluate this hypothesis. Significant decrease in calpain activity was observed in organisms exposed to the simulated geomagnetic storm whose main phase, and initial period of a recovery phase, did not coincide with the expected peak of diurnal geomagnetic variation. The results obtained are considered an experimental confirmation of the aforementioned hypothesis. Improvement of a correlative approach for the assessment of biological effects of geomagnetic activity can be achieved by considering information on the synchronization of geomagnetic storm's main phase with diurnal geomagnetic variation.

Long-Term Study of Heart Rate Variability Responses to Changes in the Solar and Geomagnetic Environment

This long-term study examined relationships between solar and magnetic factors and the time course and lags of autonomic nervous system (ANS) responses to changes in solar and geomagnetic activity. Heart rate variability (HRV) was recorded for 72 consecutive hours each week over a five-month period in 16 participants in order to examine ANS responses during normal background environmental periods. HRV measures were correlated with solar and geomagnetic variables using multivariate linear regression analysis with Bonferroni corrections for multiple comparisons after removing circadian influences from both datasets. Overall, the study confirms that daily ANS activity responds to changes in geomagnetic and solar activity during periods of normal undisturbed activity and it is initiated at different times after the changes in the various environmental factors and persist over varying time periods. Increase in solar wind intensity was correlated with increases in heart rate, which we interpret as a biological stress response. Increase in cosmic rays, solar radio flux, and Schumann resonance power was all associated with increased HRV and parasympathetic activity. The findings support the hypothesis that energetic environmental phenomena affect psychophysical processes that can affect people in different ways depending on their sensitivity, health status and capacity for self-regulation.

Influence of geomagnetic activity and atmospheric pressure in hypertensive adults

We performed a study of the systolic and diastolic arterial blood pressure behavior under natural variables such as the atmospheric pressure and the horizontal geomagnetic field component. We worked with a group of eight adult hypertensive volunteers, four men and four women, with ages between 18 and 27 years in Mexico City during a geomagnetic storm in 2014. The data was divided by gender, age, and day/night cycle. We studied the time series using three methods: correlations, bivariate analysis, and superposed epoch (within a window of 2 days around the day of occurrence of a geomagnetic storm) analysis, between the systolic and diastolic blood pressure and the natural variables. The correlation analysis indicated a correlation between the systolic and diastolic blood pressure and the atmospheric pressure and the horizontal geomagnetic field component, being the largest during the night. Furthermore, the correlation and bivariate analyses showed that the largest correlations are between the systolic and diastolic blood pressure and the horizontal geomagnetic field component. Finally, the superposed epoch analysis showed that the largest number of significant changes in the blood pressure under the influence of geomagnetic field occurred in the systolic blood pressure for men.

Synchronization of Human Autonomic Nervous System Rhythms with Geomagnetic Activity in Human Subjects

A coupling between geomagnetic activity and the human nervous system’s function was identified by virtue of continuous monitoring of heart rate variability (HRV) and the time-varying geomagnetic field over a 31-day period in a group of 10 individuals who went about their normal day-to-day lives. A time series correlation analysis identified a response of the group’s autonomic nervous systems to various dynamic changes in the solar, cosmic ray, and ambient magnetic field. Correlation coefficients and p values were calculated between the HRV variables and environmental measures during three distinct time periods of environmental activity. There were significant correlations between the group’s HRV and solar wind speed, Kp, Ap, solar radio flux, cosmic ray counts, Schumann resonance power, and the total variations in the magnetic field. In addition, the time series data were time synchronized and normalized, after which all circadian rhythms were removed. It was found that the participants’ HRV rhythms synchronized across the 31-day period at a period of approximately 2.5 days, even though all participants were in separate locations. Overall, this suggests that daily autonomic nervous system activity not only responds to changes in solar and geomagnetic activity, but is synchronized with the time-varying magnetic fields associated with geomagnetic field-line resonances and Schumann resonances.

A possible association between space weather conditions and the risk of acute coronary syndrome in patients with diabetes and the metabolic syndrome

Hyperglycemia negatively affects cardiovascular variables that are also adversely affected by increased geomagnetic activity. It is likely that geomagnetic storms (GS) could have a stronger negative impact on these patients. We analyzed data on 1548 randomly selected patients with acute coronary syndrome (ACS) who were admitted inpatient treatment in Kaunas city, during 2000-2003. We evaluated the associations of GS, solar proton events (SPE), and high-speed solar wind (HSSW) (solar wind speed ≥600 km/s) with the risk of ACS in patients with diabetes mellitus (DM) and the metabolic syndrome (MS) by using logistic regression with categorical predictors. During days of HSSW, the risk of ACS in DM patients increased by 1.95 times (OR = 1.95, 95 % CI 1.36-2.79) as compared to days without either of these events or 2 days prior to or after them. In the multivariate model, the risk of ACS in DM patients was associated with days of HSSW and 1-2 days after (OR = 1.40, 95 % CI 1.01-1.93), with days of GS lasting >1 day and occurring on days of HSSW or 1-2 days after (OR = 2.31, 95 % CI 1.28-4.17), and with the onset of SPE (OR = 2.72 (1.09-6.83)). The risk of ACS in MS patients was associated with days of GS and 1-2 days prior or after GS (OR = 1.31 (1.00-1.73)); an additional impact was established if these days coincided with days of HSSW or 1-2 days before (OR = 2.16 (1.39-3.35)). These findings suggest that not only GS but also HSSW and changes in space weather conditions prior to SPE affect the human cardiovascular system.

Associations of morbidity and mortality from coronary heart disease with heliogeophysical factors

The aim of this study was to evaluate the associations among morbidity of acute myocardial infarction (AMI) and mortality from ischemic heart disease (IHD) with heliogeophysical factors among the Kaunas population. The study population was stratified into three age categories: 25-54, 55-64, and ≥65 years. In this study, solar flares (SF), solar proton fluences (SPF), and geomagnetic activity (GMA) were employed as heliogeophysical factors and used Poisson regression and two methods of time series modeling (lag and lead). Influence of GMA in different age and sex category is uneven. The mean number of AMI events per day was greatest (23 %) among men aged 25-54 years on the third day and the same sex aged 55-64 years-increased 10 % 2 days before when the GMA intensity was A+S. Both for men and women aged ≥65 years, the highest increase in the mean number of deaths from IHD events per day was observed on the second day when the GMA intensity was A+S-51 and 34 %, respectively. Evaluating the impact of SF of 10(-5) ≤ SF < 10(-4) W/m(2) (M+X) intensity, the mean number of AMI events per day was greatest for 55-64-year-old women and men on the same and second days. Such SF were associated with a 13 and 20 % increase, respectively. Evaluating the impact of large fluence SPF, it was determined that the increase in the mean number of AMI events per day among 25-54-year-old men was greatest (30 %) 1 day, and death from IHD (54 %) was observed among women aged ≥65 years 2 days before the energy of the SPF has increased.

Effects of weather and heliophysical conditions on emergency ambulance calls for elevated arterial blood pressure

We hypothesized that weather and space weather conditions were associated with the exacerbation of essential hypertension. The study was conducted during 2009-2010 in the city of Kaunas, Lithuania. We analyzed 13,475 cards from emergency ambulance calls (EACs), in which the conditions for the emergency calls were made coded I.10-I.15. The Kaunas Weather Station provided daily records of air temperature (T), wind speed (WS), relative humidity, and barometric pressure (BP). We evaluated the associations between daily weather variables and daily number of EACs by applying a multivariate Poisson regression. Unfavorable heliophysical conditions (two days after the active-stormy geomagnetic field or the days with solar WS>600 km/s) increased the daily number of elevated arterial blood pressure (EABP) by 12% (RR=1.12; 95% confidence interval (CI) 1.04-1.21); and WS≥3.5 knots during days of T<1.5 °C and T≥12.5 °C by 8% (RR=1.08; CI 1.04-1.12). An increase of T by 10 °C and an elevation of BP two days after by 10 hPa were associated with a decrease in RR by 3%. An additional effect of T was detected during days of T≥17.5 °C only in females. Women and patients with grade III arterial hypertension at the time of the ambulance call were more sensitive to weather conditions. These results may help in the understanding of the population's sensitivity to different weather conditions.

The effect of solar-geomagnetic activity during and after admission on survival in patients with acute coronary syndromes

A number of studies have established the effects of solar-geomagnetic activity on the human cardio-vascular system. It is plausible that the heliophysical conditions existing during and after hospital admission may affect survival in patients with acute coronary syndromes (ACS). We analyzed data from 1,413 ACS patients who were admitted to the Hospital of Kaunas University of Medicine, Lithuania, and who survived for more than 4 days. We evaluated the associations between active-stormy geomagnetic activity (GMA), solar proton events (SPE), and solar flares (SF) that occurred 0-3 days before and after admission, and 2-year survival, based on Cox's proportional-hazards model, controlling for clinical data. After adjustment for clinical variables, active-stormy GMA on the 2nd day after admission was associated with an increased (by 1.58 times) hazard ratio (HR) of cardiovascular death (HR=1.58, 95 % CI 1.07-2.32). For women, geomagnetic storm (GS) 2 days after SPE occurred 1 day after admission increased the HR by 3.91 times (HR=3.91, 95 % CI 1.31-11.7); active-stormy GMA during the 2nd-3rd day after admission increased the HR by over 2.5 times (HR=2.66, 95 % CI 1.40-5.03). In patients aged over 70 years, GS occurring 1 day before or 2 days after admission, increased the HR by 2.5 times, compared to quiet days; GS in conjunction with SF on the previous day, nearly tripled the HR (HR=3.08, 95 % CI 1.32-7.20). These findings suggest that the heliophysical conditions before or after the admission affect the hazard ratio of lethal outcome; adjusting for clinical variables, these effects were stronger for women and older patients.

The influence of meteorological and geomagnetic factors on acute myocardial infarction and brain stroke in Moscow, Russia

Evidence of the impact of air temperature and pressure on cardiovascular morbidity is still quite limited and controversial, and even less is known about the potential influence of geomagnetic activity. The objective of this study was to assess impacts of air temperature, barometric pressure and geomagnetic activity on hospitalizations with myocardial infarctions and brain strokes. We studied 2,833 myocardial infarctions and 1,096 brain strokes registered in two Moscow hospitals between 1992 and 2005. Daily event rates were linked with meteorological and geomagnetic conditions, using generalized linear model with controls for day of the week, seasonal and long-term trends. The number of myocardial infarctions decreased with temperature, displayed a U-shaped relationship with pressure and variations in pressure, and increased with geomagnetic activity. The number of strokes increased with temperature, daily temperature range and geomagnetic activity. Detrimental effects on strokes of low pressure and falling pressure were observed. Relative risks of infarctions and strokes during geomagnetic storms were 1.29 (95% CI 1.19-1.40) and 1.25 (1.10-1.42), respectively. The number of strokes doubled during cold spells. The influence of barometric pressure on hospitalizations was relatively greater than the influence of geomagnetic activity, and the influence of temperature was greater than the influence of pressure. Brain strokes were more sensitive to inclement weather than myocardial infarctions. This paper provides quantitative estimates of the expected increases in hospital admissions on the worst days and can help to develop preventive health plans for cardiovascular diseases.

Geomagnetic storms can trigger stroke: evidence from 6 large population-based studies in Europe and Australasia

BACKGROUND AND PURPOSE

Although the research linking cardiovascular disorders to geomagnetic activity is accumulating, robust evidence for the impact of geomagnetic activity on stroke occurrence is limited and controversial.

METHODS

We used a time-stratified case-crossover study design to analyze individual participant and daily geomagnetic activity (as measured by Ap Index) data from several large population-based stroke incidence studies (with information on 11 453 patients with stroke collected during 16 031 764 person-years of observation) in New Zealand, Australia, United Kingdom, France, and Sweden conducted between 1981 and 2004. Hazard ratios and corresponding 95% confidence intervals (CIs) were calculated.

RESULTS

Overall, geomagnetic storms (Ap Index 60+) were associated with 19% increase in the risk of stroke occurrence (95% CI, 11%-27%). The triggering effect of geomagnetic storms was most evident across the combined group of all strokes in those aged <65 years, increasing stroke risk by >50%: moderate geomagnetic storms (60-99 Ap Index) were associated with a 27% (95% CI, 8%-48%) increased risk of stroke occurrence, strong geomagnetic storms (100-149 Ap Index) with a 52% (95% CI, 19%-92%) increased risk, and severe/extreme geomagnetic storms (Ap Index 150+) with a 52% (95% CI, 19%-94%) increased risk (test for trend, P<2×10(-16)).

CONCLUSIONS

Geomagnetic storms are associated with increased risk of stroke and should be considered along with other established risk factors. Our findings provide a framework to advance stroke prevention through future investigation of the contribution of geomagnetic factors to the risk of stroke occurrence and pathogenesis.

Short-term nitrogen dioxide exposure and geomagnetic activity interaction: contribution to emergency hospitalization for acute coronary syndrome

We investigated whether extremely geomagnetic activity may modify the association between short-term nitrogen dioxide (NO₂) exposure and emergency hospitalization for acute coronary syndrome (ACS). A case-crossover study design was used to analyze ACS in 6,594 hospitalized patients at the Clinic of Kaunas, Lithuania. We evaluated the associations between NO₂, geomagnetic activity and the rate of emergency admissions for ACS by logistic regression controlling for seasonal variation, weekdays and meteorological factors. Ambient NO₂ pollution interquartile range increase (IQR) on the day of admission and previous day (lag 0-1) in patients below 65 years of age increase the risk of ACS equal to 24% (95% CI 0.96-1.60). Evidence of effect modification by combined NO₂ and geomagnetic activity was observed in relation to ACS, adjusted OR was 1.61; 95% CI 1.03-2.53. In conclusion, these findings suggest that geomagnetic activity variations may increase the traffic-related air pollution effect on ACS, and highlight environmental factors associated with ischemic heart disease course.

Static magnetic field effect on the arterial baroreflex-mediated control of microcirculation: implications for cardiovascular effects due to environmental magnetic fields

Increasing evidence suggests that time-varying and static magnetic fields in the environment might affect the cardiovascular system. To explore the underlying physiology, the effect of static magnetic fields (SMFs) on the carotid baroreflex control of microcirculation was studied. Twenty-four hemodynamic monitorings were performed in rabbits sedated by pentobarbital infusion (5 mg/kg/h) during experiments that lasted 120 min. Mean femoral artery blood pressure, heart rate, and ear lobe skin microcirculatory blood flow, measured by microphotoelectric plethysmogram (MPPG), were simultaneously recorded before and after a 40 min exposure of the sinocarotid baroreceptors to Nd(2)-Fe(14)-B alloy magnets (n = 14) or sham magnets (n = 10, control series). The local SMF field was 350 mT, at the baroreceptors' site. Arterial baroreflex sensitivity (BRS) was estimated from heart rate/blood pressure response to intravenous bolus injections of nitroprusside and phenylephrine. A significant positive correlation was found between the SMF-induced increase in BRS (DeltaBRS = BRS(afterSMF) - BRS(priorSMF)) and the increment in microvascular blood flow (DeltaMPPG = MPPG(afterSMF) - MPPG(priorSMF)) (r = 0.66, p < 0.009). The SMF probably modulated the arterial baroreflex-mediated microcirculatory control. This could represent one possible mechanism how environmental magnetic fields act on the cardiovascular system, and a method how to complexly adjust macro- and microcirculation with potential clinical implementation.

Geomagnetic field modulates artificial static magnetic field effect on arterial baroreflex and on microcirculation

Spreading evidence suggests that geomagnetic field (GMF) modulates artificial magnetic fields biological effect and associated with increased cardiovascular morbidity. To explore the underlying physiological mechanism we studied 350 mT static magnetic field (SMF) effect on arterial baroreflex-mediated skin microcirculatory response in conjunction with actual geomagnetic activity, reflected by K and K ( p ) indices. Fourteen experiments were performed in rabbits sedated by pentobarbital infusion (5 mg/kg/h). Mean femoral artery blood pressure, heart rate, and the ear lobe skin microcirculatory blood flow, measured by microphotoelectric plethysmogram (MPPG), were simultaneously recorded before and after 40 min of NdFeB magnets local exposure to sinocarotid baroreceptors. Arterial baroreflex sensitivity (BRS) was estimated from heart rate/blood pressure response to intravenous bolus injections of nitroprusside and phenylephrine. We found a significant positive correlation between SMF-induced increase in BRS and increment in microvascular blood flow (DeltaBRS with DeltaMPPG, r=0.7, p<0.009) indicated the participation of the arterial baroreflex in the regulation of the microcirculation and its enhancement after SMF exposure. Geomagnetic disturbance, as opposed to SMF, decreased both microcirculation and BRS, and counteracted SMF-induced increment in microcirculatory blood flow (K-index with DeltaMPPG; r (s)=-0.55, p<0.041). GMF probably affected central baroreflex pathways, diminishing SMF direct stimulatory effect on sinocarotid baroreceptors and on baroreflex-mediated vasodilatatory response. The results herein may thus point to arterial baroreflex as a possible physiological mechanism for magnetic-field cardiovascular effect. It seems that geomagnetic disturbance modifies artificial magnetic fields biological effect and should be taken into consideration in the assessment of the final effect.

Does Schumann resonance affect our blood pressure?

OBJECTIVES

To investigate whether Schumann resonance (SR) affects blood pressure (BP), heart rate (HR), and depression and, if so, whether the putative BP reactivity to SR (BPR-SR) is associated with health-related lifestyle (HLS), disease-related illnesses (DRI), and depression.

METHODS

A sample of 56 adults in Urausu, Hokkaido, Japan, wore an ambulatory BP monitor, except for the time in the shower, for seven consecutive days. They completed the Geriatric Depression Scale-Short Form and a health survey questionnaire on HLS and DRI. Group mean differences and within-individual differences in systolic (S) and diastolic (D) BP, mean arterial pressure (MAP), double product (DP), and HR were, respectively, compared between normal and enhanced SR days, using Student's t-test. Correlations between BPR-SR and other characteristics (i.e. age, gender, HLS, DRI, subjective health, and depression) were analyzed, using Pearson's product moment correlation.

RESULTS AND DISCUSSION

Group mean SBP, DBP, MAP, and DP for enhanced SR days were lower than those for normal days (P=0.005-0.036). DRI was negatively associated with BPR-SR in SBP, DBP, MAP, and DP (P=0.003-0.024), suggesting a better health status for those who showed lower BP on enhanced SR days. HLS was negatively associated with BPR-SR in DBP and MAP (P=0.016-0.029). Males showed higher BPR-SR in DBP and MAP than females (P=0.004-0.016). Neither subjective health nor depression was significantly associated with BPR-SR. Future studies based on larger sample sizes are planned to see whether possible health effects can be generalized.

Chronomics for chronoastrobiology with immediate spin-offs for life quality and longevity

Effects of geomagnetic disturbance on heart rate variability (HRV), the 1/f fractal scaling in particular, are being assessed in adults living at high latitude, where magnetic storms are more frequent and more intense than at lower latitudes. The latter may constitute a signal or a proxy, and possibly a mechanism underlying both undesirable and desirable effects, depending upon circumstances yet to be elucidated. Any circadecadal stage-dependence of morbidity and/or mortality from certain conditions such as myocardial infarctions remains to be studied in both adult and pediatric populations. Further work could thus examine whether any associations of geomagnetic disturbances may account, at least in part, through effects upon the circulation, for long-term infra-annual changes, possibly anchored in the population's gene pool, observed in a number of anthropologic measurements at birth as well as in other population statistics. In order to assess the development of several chronome components of the electrocardiogram (ECG), around-the-clock ambulatory ECG were recorded from 19 infants (25 days-3 months of age), 22 children (3-9 years of age), 18 boys and girls (10-14 years of age), pubertal boys (15-20 years of age), and 10 young men (21-29 years of age). Time- and frequency-domain measures of HRV were obtained by spectral analysis, using the maximal entropy method (MEM). The frequency of detection of the circadian, circasemidian and circaoctohoran components, with periods of about 24, 12 and 8 h, respectively, was compared among the five groups for several HRV endpoints, notably 1/f fractal scaling, total spectral power within a 5-min span, and its distribution into several frequency regions. A circadian component is already detectable in a sizeable proportion of infants and children for most of the HRV indices considered. The incidence of detection of the circadian component increases with age for the spectral power in different frequency regions, notably around 10.5 s ("LF") and around 3.6 s ("HF"); it peaks around puberty for 1/f in our data; and it did not detectably change with age for the total spectral power. Similar changes with age are not observed for the circasemidian or circaoctohoran components. The latter characterizes primarily 1/f and less so the about 3.6 s power ("HF"). Several aspects of the HRV chronome may thus develop differently as a function of age. In 2000, we began a community-based study named "Longitudinal Investigation of Longevity and Aging in Hokkaido County (LILAC study)". The ambulatory blood pressure (BP) of middle-aged subjects, aged 40-74 years, was monitored 7-day/24-h, and the cardiovascular and neurobehavioral functions of elderly people above 75 years were evaluated. Our goal was the prevention of stroke and myocardial infarction and the decline in cognitive function of the elderly in a community. Of 115 elderly people recruited in a longitudinal community-based study in 2000, 72 completed yearly follow-ups in 2002. A cardiovascular score based on BP, pulse wave velocity, and 1-h ECG-based HRV endpoints served to distinguish between normal, mildly disordered, or disordered participants. A comparison of cognitive function in 2002 vs. 2000, assessed with the MMSE, HDSR, the Up & Go and Functional Reach tests, gauged any effect of social intervention. Cognitive function was maintained or improved, especially for people suffering from hypertension, tachycardia, or a decreased HRV, suggesting that cardiovascular function is a major factor affecting cognitive function.

Does exposure to an artificial ULF magnetic field affect blood pressure, heart rate variability and mood?

The aim of this study was to determine whether an artificial magnetic field with an amplitude and frequency equivalent to those of geomagnetic pulsations during geomagnetic storms could affect physiology and psychology. Three healthy volunteers wore anambulatory BP monitor and an ECG recorder around the clock for 12 consecutive weekends in Winnipeg, Manitoba, Canada. In a room shielded against ELF and VLF waves, they were exposed for 8 hours per week to either a 50 nT 0.0016 Hz or a sham magnetic field at one of six circadian stages. Real exposure randomly alternated with sham exposure. They provided saliva and recorded mood and reaction time every 4 hours while awake. Systolic (S) and diastolic (D) blood pressure (BP), and heart rate (HR) were recorded every 30 minutes. Spectral analysis of HR variability (HRV) was performed using the maximum entropy method and a complex demodulation method. For these variables, daily means were compared between real and sham exposure, using paired t-tests. Their circadian MESOR, amplitude, and acrophase were analyzed and summarized using single cosinor and population-mean cosinor. Circadian rhythms were demonstrated for HR, SBP, DBP for sham exposure, salivary flow rate, positive affect, vigor, and subjective alertness (p < 0.001, -0.02). One participant showed higher HR, lower LF, HF, and VLF powers, and a steeper power-law slope (p < 0.005, -0.0001) in an early night exposure to the real magnetic field, but not in other circadian stages. There was no significant difference between circadian responses to real and sham exposure in any variable at any circadian stage.

Geomagnetic field effect on cardiovascular regulation

The goal of the present research was try to explain the physiological mechanism for the influence of the geomagnetic field (GMF) disturbance, reflected by the indices of the geomagnetic activity (K, K(p), A(k), and A(p) indices), on cardiovascular regulation. One hundred forty three experimental runs (one daily) comprising 50 min hemodynamic monitoring sequences were carried out in rabbits sedated by pentobarbital infusion (5 mg/kg/h). We examined the arterial baroreflex effects on the short term blood pressure and heart rate (HR) variabilities reflected by the standard deviation (SD) of the average values of the mean femoral arterial blood pressure (MAP) and the HR. Baroreflex sensitivity (BRS) was estimated from blood pressure/HR response to intravenous (i.v.) bolus injections of vasoconstrictor (phenylephrine) and vasodilator (nitroprusside) drugs. We found a significant negative correlation of increasing GMF disturbance (K(p)) with BRS (P = 0.008), HR SD (P =0.022), and MAP SD (P = 0.002) signifying the involvement of the arterial baroreflex mechanism. The abrupt change in geomagnetic disturbance from low (K = 0) to high (K = 4-5) values was associated with a significant increase in MAP (83 +/- 5 vs. 99 +/- 5 mm Hg, P = 0.045) and myocardial oxygen consumption, measured by MAP and HR product (24100 +/- 1800 vs. 31000 +/- 2500 mm Hg. bpm, P = 0.034), comprising an additional cardiovascular risk. Most likely, GMF affects brainstem and higher neural cardiovascular regulatory centers modulating blood pressure and HR variabilities associated with the arterial baroreflex.

Effect of Local and Global Geomagnetic Activity on Human Cardiovascular Homeostasis

The authors investigated the effects of local and planetary geomagnetic activity on human physiology. They collected data in Sofia, Bulgaria, from a group of 86 volunteers during the periods of the autumnal and vernal equinoxes. They used the factors local/planetary geomagnetic activity, day of measurement, gender, and medication use to apply a four-factor multiple analysis of variance. They also used a post hoc analysis to establish the statistical significance of the differences between the average values of the measured physiological parameters in the separate factor levels. In addition, the authors performed correlation analysis between the physiological parameters examined and geophysical factors. The results revealed that geomagnetic changes had a statistically significant influence on arterial blood pressure. Participants expressed this reaction with weak local geomagnetic changes and when major and severe global geomagnetic storms took place.

Human head exposure to a 37 Hz electromagnetic field: Effects on blood pressure, somatosensory perception, and related parameters

Previous studies have shown that exposure to an electromagnetic field (EMF) of 37 Hz at a flux density of 80 microT peak enhances nociceptive sensitivity in mice. Here we examined the effects on pain sensitivity and some indexes of cardiovascular regulation mechanisms in humans by measuring electrical cutaneous thresholds, arterial blood pressure, heart rate and its variability, and stress hormones. Pain and tolerance thresholds remained unchanged after sham exposure but significantly decreased after electromagnetic exposure. Systolic blood pressure was significantly higher during electromagnetic exposure and heart rate significantly decreased, both during sham and electromagnetic exposure, while the high frequency (150-400 mHz) component of heart rate variability, which is an index of parasympathetic activity, increased as expected during sham exposure but remained unchanged during electromagnetic exposure. Cortisol significantly decreased during sham exposure only. These results show that exposure to an EMF of 37 Hz also alters pain sensitivity in humans and suggest that these effects may be associated with abnormalities in cardiovascular regulation.

Influence of local geomagnetic storms on arterial blood pressure

This study attempts to assess the influence of local geomagnetic storms at middle latitudes on some human physiological parameters. The blood pressure (bp), heart rate and general well-being of 86 volunteers were measured, the latter by means of a standardised questionnaire, on work days in autumn, 2001 (1 Oct to 9 Nov), and in spring, 2002 (8 April to 28 May). These timespans were chosen as periods of maximal expected geomagnetic activity (GMA). Altogether, 2799 recordings were obtained and analysed. A four factor analysis of variance (MANOVA) was employed to check the significance of the influence of four factors (local GMA level; sequence of the days of measurements covering up to 3 days before and after geomagnetic storms; sex and the presence of medication) on the physiological parameters under consideration. Post hoc analysis was performed to elicit the significance of differences in the factors' levels. Arterial bp was found to increase with the increase of the GMA level, and systolic and diastolic bp were found to increase significantly from the day before till the second day after the geomagnetic storm. These effects were present irrespective of sex and medication.

Does the timing of surgery for breast cancer in relation to the menstrual cycle or geomagnetic activity affect prognoses of premenopausal patients?

We examined the records in 36 breast cancer patients treated between 1990 and 2001, and compared them for relapse-free survival with reference to the phases of menstrual cycle defined by Hrushesky et al. and Senie et al. During the follow-up period, seven patients suffered a relapse and one died of another disease without relapsed breast cancer. The recurrence rate and relapse-free survival were not significantly different with the menstrual timing of surgery. However, patients with early breast cancer operated during the follicular phase and those with advanced breast cancer resected during the luteal phase appeared to show better prognosis than corresponding controls operated during the other phases. On the other hand, the correlation between geomagnetic activity and prognosis of breast cancer was also investigated. High geomagnetic activity during operation significantly affected the prognosis of the disease in an adverse fashion. This adverse influence was more marked in the patients operated during the luteal period. Since the menstrual cycle has no clear relation to the prognosis of breast cancer, the geomagnetic activity might affect them via other pathways than the menstrual cycle.

Verapamil protective effect on natural and artificial magnetic field cardiovascular impact

Previously we found an opposite effect of artificial static magnetic field (SMF) and natural geomagnetic field (GMF) on arterial baroreceptors. A 0.35 T SMF increased baroreflex sensitivity (BRS), whereas GMF disturbance decreased BRS. Here, we investigated interrelated impacts on arterial baroreceptors of 0.35 T SMF, generated by Nd(2)-Fe(14)-B alloy magnets, GMF, and verapamil, a Ca(2+) channel blocking agent. We measured BRS in rabbits before and after local SMF exposure of sinocarotid baroreceptors or after simultaneous SMF and verapamil application, in conjunction with geomagnetic disturbance during actual experimental run (determined by K-index) and geomagnetic disturbance over the preceding 24 h of each experiment (A(k)-index). BRS was estimated from peak responses of mean arterial pressure (MAP) and heart rate, expressed as percentages of the resting values preceding each pair of pressure (phenylephrine) and depressor drug (nitroprusside) injections. Prior to verapamil and/or SMF application we found a significant positive correlation of K-index with MAP (t = 2.39, P =.021, n = 44), but negative with BRS (t = -4.60, P =.0003, n = 44), and found a negative correlation of A(k)-index with BRS (t = -2.7, P = 0.01, n = 44). SMF induced an increase in BRS (0.79 +/- 0.1 vs. 1.15 +/- 0.1 bpm%/mmHg%, initial value vs. SMF exposure, P <.0002, n = 26). Verapamil infusion blocked the SMF and GMF effect on BRS, indicating Ca(2+) channels as a possible site of both fields' impact. SMF and GMF probably affect baroreceptor sensory transduction, modulating baroreceptor membranes' Ca(2+) channel permeability.

Artificial static and geomagnetic field interrelated impact on cardiovascular regulation

Spreading evidence suggests that environmental and artificial magnetic fields have a significant impact on cardiovascular system. The modulation of cardiovascular regulatory mechanisms may play a key role in observed effects. The objective was to study interrelated impacts of artificial static magnetic field (SMF) and natural geomagnetic field (GMF) on arterial baroreceptors. We studied baroreflex sensitivity (BRS) in conscious rabbits before and after 40 min of sham (n = 20) or application of Nd2-Fe14-B alloy magnets (n = 26) to the sinocarotid baroreceptor region in conjunction with GMF disturbance during the actual experiment, determined by K- and A(k)-indexes from a local geomagnetic observatory. SMF at the position of baroreceptors was 0.35 T. BRS was estimated from peak responses of mean arterial pressure (MAP) and heart rate expressed as percentages of the resting values preceding each pair of pressure (phenylephrine) and depressor drug (nitroprusside) injections. We observed a significant increase in BRS for the nitroprusside depressor test (0.78 +/- 0.1 vs. 1.15 +/- 0.14 bpm/mmHg%, initial value vs. SMF exposure, P <.0002) and a tendency for phenylephrine pressor test to increase in BRS. Prior to SMF exposure, a significant positive correlation was found between actual K index values and MAP (t = 2.33, P =.025, n = 46) and a negative correlation of the K index with BRS (t = -3.6, P =.001, n = 46). After SMF exposure we observed attenuation of the geomagnetic disturbance induced a decrease in BRS. Clinical trials should be performed to support these results, but there is a strong expectation that 0.35 T SMF local exposure to sinocarotid baroreceptors will be effective in cardiovascular conditions with arterial hypertension and decreased BRS, due to a favorable SMF effect on the arterial baroreflex. Magnets to the sinocarotid triangle along with modification of the pharmacotherapy for hypertension should be especially effective on days with intense geomagnetic disturbance, in moderating sympathetic activation and baroreceptor dysfunction.

Geomagnetic disturbance associated with decrease in heart rate variability in a subarctic area

BACKGROUND

Physical environmental variables, such as the natural variation in the geomagnetic field in and around the earth, influence biological processes and human health. The effect of geomagnetic disturbances on heart rate variability (HRV) in healthy students in a subarctic area is studied herein.

SUBJECTS AND METHODS

Seven-day records by Holter ECG were obtained from eight clinically healthy subjects in Alta, Norway (70 N). Frequency- and time-domain measures of HRV were compared between 24-hour spans of high geomagnetic disturbance versus quiet conditions.

RESULTS

A 5.9% increase in the 24-hour average of HR (P = 0.020) and a 25.2% decrease in HRV (P = 0.002) were documented on days of high geomagnetic disturbance. The decrease in spectral power was found primarily at frequencies lower than 0.04 Hz and was not statistically significant around 3.6 sec.

CONCLUSIONS

The physiological mechanism involved may be other than the parasympathetic, usually identified with spectral power centered around 3.6 sec, a spectral region wherein no statistically significant differences were found.

Alternating light-darkness-influenced human electrocardiographic magnetoreception in association with geomagnetic pulsations

Geomagnetic variations of partly interplanetary origin, with cyclic signatures in human affairs and pathology include the incidence of various diseases, regarding which this study of healthy subjects attempted to determine an underlying mechanism by worldwide archival and physiological monitoring, notably of heart rate variability (HRV). In the past half-century, the possible health and other hazards of natural, solar variability-driven temporal variations in the earth's magnetic field have become a controversial subject in view of the inconsistent results. Some well-documented claims of associations between geomagnetic storms and myocardial infarction or stroke have been rejected by a study based on more comprehensive data analyzed by rigorous methods - covering, however, only part of a solar cycle in only part of a hemisphere. It seems possible that inter-solar cycle and geographic variability, if not geographic differences, may account for discrepancies. Herein, we examine the start of a planetary study on any influence of geomagnetic disturbances that are most pronounced in the auroral oval, on human HRV. The magnetic field variations exhibit complex spectra and include the frequency band between 0.001-10 Hz, which is regarded as ultra-low frequency by physicists. Since the 'ultra-low-frequency' range, like other endpoints used in cardiology, refers to much higher frequencies than the about-yearly changes that are here shown to play a role in environmental-organismic interactions revealed by HRV, the current designations used in cardiology are all placed in quotation marks to indicate the need for possible revision. Whether or not this suggestion has an immediate response, we have pointed to a need for the development of instrumentation and software that renders the assessment of circadian, infradian and even infra-annual (truly low frequency) modulations routinely feasible. HRV was examined on the basis of nearly continuous 7-day records by ECG between December 10, 1998, and November 2, 2000, on 19 clinically healthy subjects, 21 to 54 years of age, in Alta, Norway. A geomagnetic record was obtained from the Auroral Observatory of the University of Tromsø. First, frequency-domain measures of HRV were compared for each person in 24-hour spans of high geomagnetic disturbance versus quiet conditions. Second, cross-spectra between geomagnetic activity and HRV measures were quantified via the squared coherence spectrum using 7-day time series. A 7.5% increase in the 24-hour average of heart rate, HR (P = 0.00020) and a decrease in HRV were documented on days of high geomagnetic disturbance. The decrease in HRV was validated statistically for the 'total frequency', 'TF' endpoint (18.6% decrease, P= 0.00009). The decrease in spectral power was found primarily in the 'circaminutan frequency', 'VLF' (21.9% decrease, P< 0.000001) in conjunction with the 'minutes-to-hours' component, ultra-low-frequency, 'ULF' (15.5% decrease, P= 0.00865) and circadecasecundan 'low frequency', 'LF' (14.2% decrease, P = 0.00187) regions of the spectrum. Power-law scaling of the power spectra did not show any statistically significant difference. It is noteworthy that most of the decrease in HRV, except for the circaminutan (VLF) component, was observed only in the season in which sunshine alternated with darkness (D/L), a finding suggesting a mechanism influenced by the alternation of light and darkness. The hypothesis of a light-dark-influenced magnetoreception was also supported by cross-spectral analysis. Group-averaged coherence at frequencies coincident with the geomagnetic Pc 6 pulsations (with periods ranging from 10 minutes to 5 hours) differed with a statistical significance (P < 0.000001) among the three natural lighting conditions, the association being weaker during UL or D/D than during D/L. By contrast, no statistically significant differences were found in terms of the circadian and circasemidian frequencies in relation to the alternation of sunshine with darkness or rather circannual rhythm stage. In conclusion, evidence is provided herein that an alteration of HRV is most apparent in the circaminutan ('VLF') region, which is clinically important, because a reduction in its power is a predictor of morbidity and mortality from cardiovascular disease. The circadecasecundan ('LF') component of HRV also decreased in association with geomagnetic disturbance, which may reflect an episodic alteration of arterial pressure related to changes in geomagnetic activity. Lastly, our study suggests the existence of a light-dark-influenced magnetoreception mechanism in humans involving mainly the Pc 6 band of the magnetic field.