The rhythms present in human beings and other creatures are considerable, including brain waves, heart beat, breathing, digestion, depth of sleep, activity, eating, as well as daily, weekly, monthly and annual cycles.
Circadian Rhythms and Chronobiology
The Journal of Circadian Rhythms is an Open Access, peer-reviewed online journal that publishes research articles dealing with circadian and nycthemeral (daily) rhythms in living organisms, including processes associated with photoperiodism and daily torpor.
Some brief quotes from the Halberg Chronobiology Center illustrate the scope of their research.
A "human" biologic week, as a feature of nature, not only culture, can be found in data from antiquity. In a histogram prepared by Hildebrandt and Bandt-Reges of the spans elapsed between the onset of symptoms and the "critical day" of fever recorded in their populations of patients by Hippocrates (c. 640 BC-c. 370 BC), Galen (c. 129-c. 200) and Avicenna (980-1037), peaks appear at 7 days and multiples of 7 days.
By 1657, Santorio's aphorisms comment on changes in body weight of one or two pounds, recurring about once a month in a mature man in a perfect state of health, who observed the utmost moderation in living. An extremely unusual case of a man who bled from his thumb about once a month is recorded, as is a purpura of the calf recurring for six years in a 60-year-old man with Morbus maculosus Werlhofii. Circatrigintans characterize the frequency of neutrophil leukocytes with "androgen-induced" nuclear appendages. In a variety of life forms, variables related not only to the reproductive tract but also to other organ systems of individuals of both genders show overt or covert cycles in the range of about 30 days. These changes can be demonstrated and validated, e.g., by the nonlinear least squares fit of a cosine curve with a 30-day period or (in cycling women) with a period corresponding to that of the menstrual cycle length (without or with the concomitant fit of harmonics).
Did you know that blood pressure is not constant but changes by more than 50 mmHg each day in most people?
Did you know that many factors can affect your blood pressure? Not only physical activitie but anxiety, other emotions, smoking, alcohol consumption, among others.
Did you know that exposure to any of these stimuli affects blood pressure differently depending on when they occur during the day?
Did you know that blood pressure disorders, if they are not treated, can lead to various complications, including heart attacks, strokes, kidney disease and retinopathy?
Did you know that treatment of blood pressure disorders can be optimized by administering the medication at the right time?
Scope of a Chronoastrobiology Research Initiative
1. The time structures of key physiological variables are to be mapped in humans and other selected species at different stages of development to examine by means of a comparative physiological approach the extent to which the evolution of the physiologic time structures can lead to testable hypotheses concerning the origins of life.
2. For these purposes, we propose to use existing devices, while developing less obtrusive diagnostic and therapeutic instrumentation as need be for the concomitant monitoring of physiological, notably, cardiovascular, and cosmo-, helio- and geo-physical variables. Even if the time structures (chronomes) in us are genetically anchored today, they may still be synchronized by or resonating with physical cycles, which may have played a role in the integrative adaptation of the rhythms in our genome.
3. Retrospective and prospective analyses of physiological records by least squares spectra, contour maps of moving periodograms, cross-spectral coherence, superimposed epochs, and "remove and replace" analyses will seek associations with concomitantly obtained physical data. The evidence is to be validated by the concordance of results from different statistical approaches and by their reproducibility at a given site and by the patterns revealed in comparisons across several geographic locations (at different geographic and geomagnetic latitudes), where participants of the BIOCOS project already have a long history of cooperation.
4. A major benefit, as a dividend from basic work will be a reference data base for the identification of disease risk syndromes and for the development of counter-measures that are best applied by closing the loop for an automated treatment, e.g. with a drug pump, a technical development that is particularly desirable in space as on earth in locations without access to hospitals.
Cases in point are too large a circadian variation in blood pressure, which is associated with a 720% increase in the risk of cerebral ischemic events, and too little heart rate variability, which is associated with a 550% increase in the risk of coronary artery disease. Putative triggers, such as the exposure to a magnetic storm, are to be further examined. Countermeasures are to be designed and applied in a timely fashion at optimal rhythm stages to lower risk and maintain health.
Chronoastrobiology is derived from chronome (time structure) and astrobiology. It is a branch of biology concerned with life's origins and worlds before ours as they may be reflected in the current temporal organization of physiological functions. The goals of this research initiative are pursued by a coordinated comparative physiological and physical (and when pertinent, archival) monitoring and analysis. An initial attempt to elucidate factors with implications to chronoastrobiology is a project on the BIOsphere and the COSmos, called BIOCOS. This international endeavor has already yielded a major benefit in the form of the definition of elevated disease risks and of the sampling requirements for their reliable detection as steps toward risk reduction on earth, as a model for use during travel in extraterrestrial space.
Hardware and software will be improved for unobtrusive coordinated physiologic and physical monitoring. As a dividend from monitoring, a major benefit will be the detection of an elevated disease risk and its reduction by the timely institution of countermeasures. These tasks gain in importance for NASA as humans venture further and further into space. The unobtrusive equipment to be developed for this project will be available to screen candidate astronauts prior to missions to the moon, Mars, and beyond, and for data collection during these missions for basic science and health surveillance.
The University of Minnesota Chronobiology Laboratories in cooperation with the NASA Ames Research Center, San Jose State University, and a group of foreign investigators in different geographic locations will monitor the broad rhythmic and other time structure of selected vascular and other variables during human ontogeny. This will be done in a comparative physiologic context on earth, and as far as possible in space, thereby to focus on helio- geophysical time structures that may have existed at the sites of life's origins, wherever they may have been, on or away from earth.
For these purposes, the data base on selected existing organisms, dubbed "living fossils", accumulated at the University of Minnesota Chronobiology Laboratories over the past 50 years will be organized, analyzed, and regularly updated in view of the data flow from around the world continuing to accumulate in these laboratories. In particular, data on vascular markers (blood pressure, heart rate and other circulatory variables) will be summarized in a book form and as a web site made available through NASA to all interested parties. On the web site, educational chronoastrobiology materials will provide basic knowledge of onešs functions and origins, in the context of instrumented self-care.
Focus is required on extra-circadian and circadian rhythms. These are superimposed on seemingly chaotic changes. Physical changes, as events or continuous records, monitored concomitantly, will be analyzed for matches or near-matches between geophysical features and biological ones, on earth and in space, retrospectively as well as prospectively. Periodicities or other patterns found in one field, such as half-yearly patterns in geophysics, will lead to exploration of their numerical counterparts in the other fields, such as those of biomedicine (i.e, the half-yearly pattern in epilepsy) and vice versa, as a first step.
Cross-spectral coherence, less unspecific than a product moment correlation, will be sought between geomagnetic pulsations and features of the electrocardiogram (and eventually of the electroencephalogram). Initially, associations already uncovered will continue to be mapped and further explored. For instance, close examination of biology has led to the discovery of geophysical periodicities, as in the case of the built-in about-weekly component, which found its way into our culture and was uncovered as part of our genetic (human or crayfish) and geophysical (magnetic disturbance-related) environmental nature. vice versa, a geophysical periodicity, such as the half-yearly feature of geomagnetic disturbance, has led to biological numerical matches, as in the case of the half-yearly distribution pattern of over 50,000 cases of status epilepticus. Such parallels between physiology and physics will continue to be mapped and further explored.
Each association among physiologic and physical phenomena will have to be scrutinized, whenever possible, by both archival and physiological monitoring, with a battery of analytical procedures. These range from cross-spectral coherence and superimposed epochs, to a "remove and replace" approach. The latter mimics what is done in endocrinology when a gland is removed and its product, the hormone(s), is then administered as a replacement. By the same token, physically recorded changes in the solar or extra-solar system will be examined for associations with changes in biological variables, examined in monitored physiological time series. A case in point is the presence or absence of 7-day patterns in the velocity changes of the solar wind, as they are associated with an amplification or dampening, respectively, of about 7-day changes in human heart rate.
Scrutiny of physiological time series recorded concomitantly with the physical variables in strategically placed locations on earth, and whenever possible in space, will allow the mapping of the relative prominence of photic (electromagnetic radiation, notably but not exclusively in the visible domain) and non-photic (corpuscular emissions, heliogeomagnetics, gravitation and other) effects from the sun and/or from beyond the solar system and their dependence upon latitude. As an example of the need for extra- circadian study, we cite the case of endothelin-1 (ET-1), the most potent vasoconstrictor in human blood. While a circadian variation was not demonstrated in ET-1, about 3.5-day and about 8-hour components were discovered as characterizing ET-1 concentrations in human blood. A follow-up finding in the mouse was that the population density of endotheliocytes, the cells producing ET-1, is also characterized by the prominence of extra-circadian components of variation with frequencies similar to those noted in blood. Whether or not the additional clinically relevant finding that the about 3.5-day pattern is altered in the presence of vascular disease risk is of potential usefulness for screening astronauts, the fact remains that in the same circulation ET-1 may be about 8-hour periodic while cortisol is about 24-hour periodic.
The search for physical and/or biologic mechanisms underlying these and other extra-circadian rhythms is on the agenda next, as a test case of the hypothesis that some features of our current time structure result from an internal as well as Darwinian evolution. The survival of the fittest depends upon an internal integrative rather than only on an externally adaptive evolution.