. we explore circadian and infradian rhythms in time estimation ( te ) , having shown that the stage of the former is essential for the assessment of the latter in the case of a half - year - long spectral component probably related to geomagnetics in human systolic blood pressure ( sbp ) ( tarquini et al 1997 ; halberg et al 2001a ; cornlissen et al 2002 ; sothern et al 2006 ) . we here ask whether changes with age in a mental function , such as the te of an 1-minute duration , also differ as a function of circadian stage . our test of mental functioning for precisely timed action is performed inexpensively , without the need for bulky instrumentation beyond a stopwatch . the test is quick and easily repeated , and may also tell us whether and , if so , when one aspect of subjective time what is particularly important , the circadian components here mapped could serve as a marker for interventions , therapeutic or other . te is a basic and critical feature and index of mental processes ( piaget 1946 ; fraisse 1963 ; geissler and reschke 1987 ) . a circadian rhythm characterizes several approaches to estimating 2 minutes under conditions of 24-hour synchronization with ( stephens and halberg 1965 ) or desynchronization from ( halberg et al 1965 ; siffre et al 1966 ; halberg and reinberg 1967 ; ghata et al 1968 ; halberg 1968 ; wever 1979 ) a societal routine . the circadian rhythm persists under conditions of isolation from society with a concomitant decrease of the ratio  subject time / environmental time  ( cf . such results extend earlier pioneering studies by macleod and roff ( 1935 ) and were confirmed and extended by follow - ups that also considered putative effects of cosmic factors ( hillman et al 1994 ; halberg et al 1998 ) and infradians ( sanchez de la pea et al 1989 ) , among others . whether or not a change in ratio of subjective / environmental time during isolation relates to the lengthening of the desynchronized circadian rhythm in 2-minute te and in other variables , noted in most humans studied thus far ( wever 1979 ) , remains to be investigated in a broader context ( fraisse 1963 ; geissler and reschke 1987 ; glicksohn 1992 ; halberg et al 2001a ; eagleman et al 2005 ) . for example , when the subject of this paper ( rbs ) spent 19 days in social isolation near the beginning of his 40-year self - measurement project , the period of his circadian rhythm in 2-minute time estimation increased ~4% , from 24.0 to 24.9 hours , while the 24-hour mean increased about 22%25% , from about 150 s to 188 s ( unpublished observations [ cf . halberg et al 1972 ] ) . both a decrease in circadian amplitude during isolation and an increase in circadian amplitude after isolation are seen in figure 2c for the rhythm in core temperature ( top ) and 2-minute estimation ( bottom ) , along with a delaying drift of the acrophases due to a lengthening of period . hypothesized that the more varied the sensory environment ( ie , perceptual overload versus perceptual deprivation ) , the longer the time that is verbally estimated , and the shorter the time estimation obtained by the method of production  . his data on 96 subjects exposed to various combinations of auditory and visual stimulation gathered by the latter method agreed , but not those with the former method . he concluded that  visual and auditory stimulation interact in their production of an altered sensory environment , and that the rate of functioning of the cognitive timer is environment dependent .  eagleman and colleagues ( 2005 ) review  new discoveries in psychophysics , electrophysiology , imaging , and computational modeling [ that ] are contributing to an emerging picture of how the brain processes , learns , and perceives time , emphasizing that  most of the actions our brains perform on a daily basis , such as perceiving , speaking , and driving a car , require timing on the scale of tens to hundreds of milliseconds .  sothern and colleagues ( 2007 ) most recently found a near - transyearly period ,  ( 1.00 year < [   ci { 95% confidence interval } ] < + ci ] < 1.20 years ) , and several far - transyearly s ( 1.2 years  [   ci ] < [  + ci ] < 1.9 years ) in 1-minute te ( about 5 times a day for 35 years ) as a magnetoperiodism , with a differential congruence of these near- and far - transyear periods with the periods of cycles in the solar wind s speed and geomagnetics . here we focus on the photic circadian and other rhythm - stage dependence of changes in 1-minute te and on any effects of age . for 3.5 decades , 1 minute was estimated by counting two to seven times daily ( on the average about 5 times / day ) , by a clinically healthy man ( rbs ) , who started estimating 2 minutes by counting at ~20.5 years of age in 1967 . in view of differences between te of 2 minutes , performed at the start of monitoring for ~3 years and subsequent 1-minute te continued a year later for 3.5 decades , only data from the longer 35-year record ( of 1-minute te ) are here considered . data were analyzed spectrally , by the extended linear - nonlinear cosinor ( halberg 1980 ; cornlissen and halberg 2005 ; refinetti et al 2007 ) with parameter tests ( bingham et al 1982 ; cf . halberg et al 2003a ) and by comparing the first and the last year s original data in 8 time - of - day bins of 3 hours each with student s t - test and all 8 timepoints by a paired t - test . in figure 3 , the periodogram of rbs s data is plotted linearly in frequency , yet with periods given on top for each half of the figure , the upper half summarizing results at 25 years of age , and the lower one at 60 years of age . the original ordinate at the bottom of each , the upper and lower halves , is given on the right . in the insert of each half , the ordinate is truncated to prevent the dominating circadian from obscuring lower - than - circadian frequencies ( infradians ) . the inserts show that with advancing age ( lower vs upper half ) , some frequencies differ in prominence . while a circaseptan and a circasemiseptan component are detected with statistical significance at both ages , a 30-day component is detected prominently only at the younger age . at 60 years of age , a 1-year component s prominence is replaced by that of a half - yearly component , probably of geomagnetic ( nonphotic ) origin ( cornlissen et al 2002 ) . figure 4 provides a highly qualified yet clear answer to the question whether there is an acceleration of the subjective  minute  with age in rbs . this figure stacks data in two chronograms along the 24-hour scale , each summarizing a year s data 35 years apart , at 25 vs 60 years of age , respectively . without extrapolating to other subjects ( halberg et al 1981 ) and/or to the intervening years , admittedly great limitations , both the ( sparsely documented ) maxima and some of the ( solidly documented ) minima ( numbers of te at each time are given in parentheses ) are numerically lower during year 35 than during the first year ( figure 4 ) , ie , at 60 vs 25 years of age , suggesting acceleration . figure 4 shows further that even if overall the time - structure - adjusted mean ( mesor ) is numerically lower at an advanced age , the demonstration of an age change is not possible on this basis ( p = 0.300 ) . a circadian stage - dependence in figure 4 is found by student t - tests that show an aging effect in rbs to be not demonstrable at certain circadian stages , while it is statistically highly significant at other times of day ; each result , that around 10:30 vs that at 19:30 , is documented with relatively ample data . these results , albeit amply documented for rbs , can not be extrapolated to others . in another case , hl , a physician with aldosteronism , the estimation of 2 minutes took longer at 63 years of age than it did at 53 years , as if time passed more slowly in this particular elderly man ( halberg et al 1981 ) . while in hl the change during a decade seems to be linear , it was nonlinear over several decades in the yearly and transyearly amplitudes of rbs heart rates ( hr ) ( sothern et al 2004 ) and what it was in te remains to be assessed . assessed for rbs and hl may perhaps be reconciled , at least in part , by the presence of low - frequency cycles . in the case of rbs , even decade - long records may thus exhibit either an increasing or a decreasing trend depending on when during this about 26-year cycle monitoring took place . a similar situation was encountered in a 15-year record of urinary excretion of 17-ketosteroids characterized by an about 10-year cycle ( halberg et al 2001b ) . in the case of rbs , subjective time elapsed during the 19 days of isolation was shorter by 17.5 hours or ~4% . this is contrasted with 2-minute time estimation by rbs that was increased by 25% from ~150 to ~188s , suggesting a dissociation between short - term and long - term time perception , the difference along the two time scales possibly accounted for , at least in part , by the rest - activity cycle , which provides an important clue of elapsed time along the scale of days . differential congruence of periods ( s ) in helio- and/or geomagnetics and in human psychophysiology is also documented for rbs assessed ( by overlying or overlapping 95% confidence intervals ) of s found in a mental function ( 1-minute te ) and in sbp and hr in about 4 decades of around - the - clock self - measurements ( sothern et al 2007 ) . a combination of the extended cosinor by nonlinear analyses complemented by a population - mean cosinor summarizes the same series analyzed in consecutive subsections . there are corresponding s in te , sbp and hr themselves and in the spectrum of solar wind speed and in geomagnetics ( aa index ) for several orderingly statistically significant peaks between trial s of 2.0 and 0.7 years ; this congruence differs among variables and s involved ; it is differential . 5 of 8 sbp peaks are congruent with the solar wind in the spectral window examined at s different from a calendar year , as are 3 of the 4 sbp peaks that are congruent with geomagnetics . congruence of sbp with magnetoperiodisms occurs in the presence of a large photoperiodic annual component in sbp . congruence of s with solar wind is 3 out of 7 for hr and 5 out of 10 for te , and with geomagnetics it is 2 out of 7 for hr and 4 out of 10 for te . different physiological variables and even the same variable s different spectral components may be influenced by different environmental s . while no congruence in all 5 variables was seen , all 3 psychophysiological variables were congruent with richardson s ~1.3-year oscillation in solar wind speed during the span of rbs s data . congruence among an as - yet undefined fraction of s in other physical and biological variables monitored by rbs and others is also differential ; it is not conclusive in itself but is desirable for a follow - up by superposed epochs and by comparison of time courses of s in and around us , whenever rendered possible due to removal and replacement of intermittent s by the sun and earth . magnetoperiodism coexists and competes with photoperiodism to influence dynamics in the same individual and can dominate in te in the range of near - transyears , while photoperiodism dominates in the circulation of the same individual in both the para - annual and circadian spectral domains . in any event , figure 4 suffices to infer that in the estimation of subjective time different aspects of the body s temporal make - up interact in a circadian stage - dependent way in the case of rbs ; hence , age - dependent acceleration in estimation of 1 minute is best specified as to circadian time and probably as to other rhythms stages so that a different outcome , such as an acceleration vs no age effect , and in another case ( hl ) opposite inferences , can be taken at face value . on the positive side , the recognition of cycles , including non - photic ones such as transyears , in time estimation that differ from the photic day and year opens new perspectives of how a mental function can be influenced by the solar wind s cyclicities that may have entered the genome , as circadians clearly did ( touitou and haus 1992 ; halberg et al 2003b ; koukkari and sothern 2006 ; refinetti 2006 ) . the importance of nonphotic cycles beyond those in the estimation of 1 minute is evident from those influencing sudden death ( halberg et al 2006 ) , suicide ( gordon and berk 2003 ; berk et al 2006 ; cornlissen and halberg 2006 ; shumilov et al 2008 ; chernouss et al pers comm ) , terrorism ( cornlissen et al 2007 ; grigoryev and vladimirskii 2007 ; halberg et al 2007 ; wendt 2007 ) , and psychophysiology more generally ( persinger 1987 ; oraevskii et al 1998 ; breus et al 2002 ; palmer et al 2006 ) . in a follow - up study focusing on the years intervening between ages 25 and 60 , opposite effects at different circadian test times could be validated with statistical significance . these findings extend the scope of the comparison of the first and the last year of a 36-year record , which latter sufficed to show that one can have different results concerning aging , depending on when along the scale of a day , 1 minute is estimated by counting . a 1-minute duration passed faster at 60 vs 25 years of age at some circadian stages , eg , between 09:00 and 12:00 , while at other circadian stages no difference or an opposite trend between 18:00 and 21:00 ( r = 0.400 , p = 0.010 ) was detected . if one examines the change with age of hormones in women , one finds an increase ( p < 0.001 ) for lh and a decrease for e2 ( p < 0.001 ) ( halberg et al 1981 ) . decreases are also found for aldosterone , melatonin and in particular for dehydroepiandrosterone sulfate ( halberg et al 1981 ; cornlissen et al 2000 ) . accordingly , a change in amplitude with age , ceteris paribus , will involve necessarily as a function of age opposite results at the circadian peak versus trough : an increase in amplitude will have a corresponding increase at the time of circadian peak and a decrease at the time of circadian trough and vice versa in the case of a decrease in amplitude there will be a decrease at the time of circadian peak and an increase at the circadian trough . this applies to circadian rhythms and has been documented in halberg and colleagues ( 1981 ) and cornlissen and colleagues ( 2000 ) . similar effects will apply to any other cycle changing with age and controversies will be unavoidable even if the time of day is fixed but chosen differently in various studies , according to investigators convenience . a further complication is also relevant to studies on aging between just reaching maturity and at 60 years of age . a plethora of aeolian cycles , figure 5 , are characteristic of many functions monitored not only by rbs but also on over a dozen other subjects of both genders with decades - long time series . many of these spectral components are of non - photic origin , coexisting and competing with , and sometimes replacing the calendar - year component . these cycles constitute pertinent control information and are also of interest in their own right , since some of them are associated with suicide ( cornlissen and halberg 2006 ) and sudden cardiac death ( halberg et al 2006 ) . aging can be studied without or with chronomics : so it appears to be the case today . but if opposite inferences are drawn at different circadian stages , as documented herein and earlier for another subject , sbs ( sothern et al 2006 ) , it seems possible that we may generalize and consider requiring the time of day as an indication in all studies of human aging . this seems indicated based on evidence available today , so that controversies are avoided and expensive long - term studies must not be repeated . moreover , an indication of calendar date in any and all studies of aging seems to be similarly required , since some of the cycles documented here and elsewhere can be signatures of environmental periodicities , which latter are recorded by governmental agencies and can thus be consulted and used for computing reference cycles . for human mental function , there is a saying : use it or lose it . when to use it , to avoid the loss of cognitive function , and when to treat , is already extensively documented for circadians and may also apply to infradians , for instance , since negative affect is primarily circaseptan periodic , while positive affect is dominantly circadian ( cornlissen et al 2005 ) , as shown herein for mental functioning by the proxy of time estimation . the amplitudes of the new rhythms mapped may be small , but small amplitudes are compatible with large and important associations ( halberg et al 2003c ) . the circadian amplitude in the mental function mapped along the age scale remains large and may serve immediately for timing intervention ; timing , like dosing , has demonstrated , albeit as yet not routinely utilized , therapeutic benefit .
backgroundcircadian rhythm stage affects many outcomes , including those of mental aging.methodsestimations of 1 minute ~5 times / day for a year , 25 years apart , by a healthy male biomedical scientist ( rbs ) , are analyzed by the extended cosinor.resultscycles of a half - week , a week , ~30 days , a half - year and a year , in self - assessed 1-minute estimation by rbs between 25 and 60 years of age in health , are mapped for the first time , compared and opposite effects are found . for rbs at 60 vs at 25 years of age , it takes less time in the morning around 10:30 ( p < 0.001 ) , but not in the evening around 19:30 ( p = 0.956 ) , to estimate 1 minute.discussionduring the intervening decades , the time of estimating 1 minute differed greatly , dependent on circadian stage , being a linear decrease in the morning and increase in the evening , the latter modulated by a ~33.6-year cycle.conclusioncircadian and infradian rhythm mapping is essential for a scrutiny of effects of aging . a ~30-day and a circannual component apparent at 25 years of age 
 are not found later ; cycles longer than a year are detected . 
 rhythm stages await tests as markers for timing therapy in disease .