Indian J Physiol Phannacol1994; 38(2) : 101-107

CHARACTERISTICS OF IN SIX VARIABLES OF MORNING ACTIVE AND EVENING ACTIVE HEALTHY HUMAN SUBJECTS

S. GUPTA AND A. K. PATI

School ofLife Sciences. Pr. Ravishankar Shukla University, Raipur - 492 010

( Received on April 18, 1993 )

Abstract: Ten apparently healthy human subjects, inhabitants of dry and hot tropical climate. volwlteered for the study. They were instructed to self-measure, several variables, such as oral temperature, heart rate, subjective fatigue, subjective drowsiness, finger cOWlting speed and random number adding speed, daily, pn:ferably at an interval of 4h. for 10-15 days. However, they were instructed to have ad libilum and not to truncate sleep for the sake of self-measurements. The subjects were categorized into two groups. viz, morning active and evening active and their circadian time structu:e in the above mentioned variables was studied. The results clearly show a higher order of internal synchronization among all the variables. Comparison of acrophase locations between morning active and evening active individuals reveals that the pcaks in oral temperature. heart rate and random number adding speed occurs earlicr in morning active individuals (P

Key words: circadian rthyhm morning active

evening active amplitude

INTRODUCTION identified in the local population with the help of specially designed questionnaire (7.8,9) and their It has been well established that rhythms in circadian time structure was studied. various physiological, immunological, psychological and behavioural end points, under natural conditions, METHODS exist and exhibit periodicity of about 24 h (I, 2, 3, 4, 5, 6). Most of the studies performed in human Subjects: Ten apparently healthy subjects circadian rhythms have been restricted to the temperale inhabitant of Raipur (19°50' to 21 °53' Nand 81 °25' to regions of Ihe world. Climalic conditions have been 83 238' E) volunteered for the study. Various biometric reponed to interfere in the process of rhythm and physiologic characterstics of the subjects are shown synchronization or desynchronization. However, it is in Table I. During the cours~ of this study, the subjects not well documented as to, howfar, climatic conditions followed their normal routine and were instructed to specially of tropical regions could influence the pattern maintain daily diary. No restriction was imposed of circadian rhythms. upon their sleep schedules. They were allowed to sleep ad libitum during the customary timings. The present study included subjects those represent human population living in hot and dry tropical climatic Data collection: The subjects were instructed to conditions of Raipur 19°50' to 21°53' Nand 81°25' to self-measure several variables, such as oral temperature 83°38' E. Two types of , such as morning (OT), heart rate (HR), subjective fatigue (SF), active individuals and evening active individuals were subjective drowsiness (SDR) (10), finger counlinJ! 102 Gupta and Pati Indian J Physiol Pharmacol 1994; 38(2)

TABLE I: Biometric and physiologic characteristics of 10 diurnally active healthy human subjects.

Subject Sex Age Weight Height BSA Chronotype Code (y) (kg) (cm) (rrr)

C 1# 01 (AK) M 22 50 165 1.53 MA

C 1# 02 (RR) M 25 53 165 1.57 EA

C 1/ 03 (PS) F 23 52 162.5 1.54 MA

C 1# 04 (IVG) F 23 50 160 1.5 MA

C 1# 05 (AD) F 25 43 156.2 1.38 MA

C 1/ 06 (OS) F 22 58 170.0 1.67 EA

C 1# 07 (NM) M 24 50 157.5 1.48 MA

C 1# 08 (SAC) M 22 50 162.5 1.52 EA

C 1# 09 (MST) M 23 64 170.0 1.74 EA

C 1# 10 (SJ) F 25 42 147.5 1.31 MA

Body surface area (BSA/m') was obtained by Du Bois's formula. MA stands for morning active and EA for evening active. speed (FeS) and random number addition speed special statistical techniques, t-test was also used to (RNAS) (11), every 4 h, except during sleep, on compare averages. daily basis at least for 10-15 days. Prior to the beginning of data colIection, each subject was given Morningness vs Eveningness : Morningness or data sheets, stop watch and clinical thermometer and eveningness in each subject was detected on the basis was trained to use those properly. The subjects were of a specially designed questionnaire. This was a also provided with questionnaires to obtain information shortened and simplified version of the questionnaire on their day to day sleep quality and quanlity. During used by Ostberg (7). Such identifications were further the actual experimental periods, random checks were confirmed by the results of the cosinor rhythmometry with a special reference to phases of individual's undertaken to ensure that the various self-measured variables are properly recorded. In case of any circadian rhythm in oral temperature (7,8,9). discrepancy, the whole 24-h data of that particular subject RESULTS was rejected. In the present study, out of 10 subjects, 6 were Statistical analysis: The self-measured variables found to be morning active and the remaining four were analysed for documenting a circadian rhythm were evening active. (period =24 h) with the help of cosinor rhythmometry (12, 13). Various end points, viz., mesor (rhythm­ Circadian periods: Prominent circadian periods adjusted mean), amplitude (half the difference between for rhythms in all the six variables in each subject are the highest and the lowest value) were computed. A presented in Table II. When the results of spectral power spectrum method (14) was used to detect analysis were pooled. irrespective of variable and prominent period in the time series for each subject personality of the subjects (Fig. 1), the frequency of and for each variable. It has now been clearly 24 h period was 70%. In addition, 23% time series had demonstrated that missing data during sleep do not period at the first circadian harmonics (i.e., period = alter circadian rhythm parameters, viz., period, mesor, 12 h). The remaining 7% time series neither exhibited amplitude. and acrophase (15). Apart from the above exactly 24 h period nor 12 h period (Fig. 1). Fig. I Circadian Rh)1lwn in lIum8ll SubjcClS 103 Indian J Physiol Pharmacol 1994; 38(2)

POOLED VARIABLES

Non-circadian 7%

1st Harmonics 23%

ORAL TEMPERATURE HEART RATE SUBJECTIVE FATIGUE

Non-olroadlan 10'11 11t HarmonlOl 20$

1st Harmonica 1al Harmonica 20$ .0'11 RANDOM SUBJECTIVE DROWSINESS FINGER COUNTING SPEED NUMBER ADDITION SPEED

Non-olrowlan 10'11

1s1 Harmonica let Harmonlot ~O$ 10$

Fig. 1 : Individual and group frequcncy of circadian (t =24 h), ultradian (1: = 12 h, i.e., exactly of the first circadian hannonies) and non· circadian (1: =24 hand/or 1: ~ 12 h) rhythms in 6 variables. 'Ihe data. from all the 10 healthy human subjects have been pooled. 'Ilie frequency of circadian periods was the dominant feature (see also Table II) and non-circadian rhythms were absent in heart rate, subjective fatigue and drowsiness. ·By power spectrum analysis 'Prominant period, if the first one is not 24 h

Other details on subjects liS in Table I OT, Oral temperature; HR, Heart rate; SF, Subjective fatigue; SDR. Sublectivc drowsine..; FCS, Finger counting speed; RNAS. Random number addition speed. ;:..Or:..:..=--..=mpe~r.='ur=-. ---, 3T.'6 also depicts the results of power spectrum analysis for each variable separately. The highest frequency of circadian periods was a dominent feature for each 38.95 I variable. Non-circadian (i.e.• period -:I- 24 or -:I- 12 h) 38.76 rhythms could not be detected at least for 3 variables, such as heart rate, subjective fatigue and subjective ~ drowsiness. However, when data were grouped for u ..

morning active and evening active subje::ts sepMately, 38.36 04 08 '.l.-2-'--16--'----'-2J..O-'----'OO----'---'O~--'----J0'-8--'----''-2--'-'-'-6-'-2-'-0-'--'00 the non-circadian period were detectej in the evening 00 active persons only (Table III). - MornIng ""II.. --+-- Ewenlnll ""II..

Rhythm. detection: Statistically significant circadian rhythm was validated for each variable and each subject. However, subject C -:I- 08 was the only exception, not shown here, in that the null hypothesis of zero amplitude was accepted for the daily variation in subjective fatigue. Fig. 2 shows group cosine curves for OT, HR, FCS and RNAS in both morning active and evening active subjects. However, it was not possible to draw group cosine curves for SF and SDR because of higher degree of interindividual variation in these variables. However, - Morning aoll.a --;- ~.anlng sell.a Fig.2a: An illullrativcexample of circadian rhythm in oral for these two variables, individual cosine curves have temperature DC and heart rate (beats/min) of morning active been shown taking into cosideration two selected an

TABLE 111: Showing the frequency of occurrence of circadian and non-circadian periods for six variables in human subjects.

Morning active Evening active

Circadian lsI Non­ Circadian 1st Non­ Harmonics circadian Harmonics circadian

Variable OT 5 o 2 HR 3 3 o 3 o SF 5 o 2 2 o SDR 5 o 2 2 o FCS 6 o o 2 RNAS 5 o 2 TOTAL 29 7 o 12 8 4 PERCENT 81 19 o 50 33 I7

Other details as in Table II. Finger counting .peed_ 17.-=------=-.....:.------, individuals one from each morning active (C :t 03) and evening active (C :t 02) groups (Fig. 3).

14

- Morning active -I- Evening active Random number addition apeed

68

ti3

48 '--l....-l....-l....-L....JL....JL...JL...JL...JL...J--'--'--'--'--'--'---'---'---'---'---'---'---'--l -- Morning active -1- e.,enlng active 00 04 08 12 16 20 00 04 08 12 16 20 00

- Morning active -I- Evening active rig. 2b: An illustrative example of circadian rhythm in finger Fig. 3 : An illustrative example of circadian rhythm in subjective counting peed (seconds) and random number adding fatigue and subjective drowsiness of a morning active (C#02) speed (seconds) of moming aClive and evening active and an evening active (C#03) suhjecl. suhjects. 106 Gupta and Pati Indian 1 Physiol Phannacol 1994; 38(2)

Group averages were computed for mesors, DISCUSSION amplitudes and acrophases for each variable under study with respect to morningness and eveningness. The Results of this study clearly demonstrate that data are presented in Table IV. When morning variables under investigation show higher order of active and evening active groups were compared intern~l synchronization in terms of length of period with each other, it was found that there was no and that the circadian period is the dominant feature statistically significant difference between both for almost all the variables. The non-circadian component circadian mesors and amplitudes, excepting in the pooled data was negligible (only 7%). The circadian mesor in the rhythm of finger counting detection of this component was restricted among speed (Table IV). However, when acrophase locations evening active subjects. Could it be that evening active were compared it was noticed that peaks in oral perosns suffer from internal desynchronization of temperature rhythm and heart rale rhythm occurred rhythms? It is remarkble that in general the next earlier in morning active individuals (Table IV; P

TABLE IV : Comparison of rhythm parameters between morning active (MA) and evening active (EA) subjects.

Rhythm df Amplitude df Acrophase df Variables adjusted t A ± j SE t ¢ ± j SE t mean, M+j SE P P P MA EA MA El. MA EA

Oral 36.86 36.60 7 0.27 0.19 8 14.5 19.4 8 temperature ±0.09 ±0.14 1.562 ±0.05 ±0.06 1.024 ±0.85 ±0.55 4.84 NS NS <0.002

Hean 75.49 68.12 8 4.19 3.99 8 15.23 17.78 8 rate ±2.02 ±4.29 1.554 ±0.81 ±1.78 0.102 ±0.23 ±0.53 4.414 NS NS <0.005

Subjective 05.90 05.87 8 6.14 4.91 8 23.53 21.23 8 drowsiness ±1.19 ±1.59 0.~15 ±1.39 ±1.88 0.526 ±0.5 ±2.19 0.979 NS NS NS

Subjective 07.18 06.94 8 4.64 5.22 8 23.28 21.23 8 fatigue ±1.51 ±1.54 0.111 ±0.98 ±1.58 0.312 ±0.29 ±1.75 1.56 NS NS NS ringer 12.91 15.42 8 0.66 0.98 8 00.5 04.7 8 counting ±0.49 fOAl 3.929 ±0.06 ±0.22 1.403 ±0.67 .1:2.17 1.847 speed <0.005 NS NS

Random 52.75 63.13 8 3.42 6.14 8 21.7 06.53 8 number ±2.63 ±4.23 2.084 ±0.43 ±1.29 2.0 ±1.05 ±1.65 7.757 addition NS NS <0.001 speed df =degrees of freedom t =t-value (Student's t-test) P =probability level !l:S =not significant Indian J Physiol Pharmacol 1994; 38(2) Circadian Rhythm in Human Subjects 107

When the data were grouped on the basis of phase position in body temperature rhythm (6, 18, 19, morningness and eveningness it was observed that later 20, 21). The present results demonstrate phase individuals have poor eye-hand coordination ability. advancement of HR rhythm in morning active individuals, in addition to OT rhythm reported earlier. As regards phase position of several rhythms studied herein, statistically significant difference was The other important finding of the present study witnessed in circadian rhythms oforal temperature (OT), relates to rhythm in random number addition speed. heart rate (RR), and random number addition speed The morning active subjects were at their best between (RNAS) only. In both OT and HR rhythms, the circadian 8.6-10.7 h for this task, whereas evening active subjects acrophases (peaks) occurred earlier in morning active had their best time between 16.9-20.2 h. individuals than that in evening active individuals. ACKNOWLEDGEMENTS The results of the present study coroborate the findings reported earlier in that the morning types show We are greatful to CSIR for the award of senior advancment and evening types delay in their circadian research fellowship to one of us (SG).

REFERENCES

1. Reinberg A, Andlauer P, Guillet P, Nicolai A. Oral temperature, 11. Halberg r, Johnson EA, Nelson W, Runge W, SOlhem R. circadian rhythm amplitude ageing and tolerance to shift-work. Autorhythmometry procedures for physiologic self-measunncnts Ergonomics 1980; 23: 55-64. and their analysis. Physiology Teacher 1972; 1: I-II. 2. Halberg F. Biologic rhythms, and aging. In : 12. Nelson W, Tong YL, Lee JK, Halberg F Methods for cosinor­ "Honnones in development and Aging", Vemadakis A, Timiras rhythmometry. Chronobiologia 1979; 6: 305-323. PS (eds), Spectrum publications, New York, 1981; 451-476. 13. Gupta S, Pati AK. Data analysis methodology in chronbiological 3. Pati AK, Florentin J, Chung V, De Sousa M, Levi F, studies. J Parasit Appl Anim Bioi 1992; \; 151-163. Mathe G. Circannual rhythm in natural killer activity and 14. De Prins J, Cornelissen G, Malbacq W. Statistical procedures mitogen responsiveness of murine splenocyles. Cell Immunol in and chronopharmacology. Ann Rev 1987; 108: 227-234. Chronopharmacol 1986; 2: 27-141. 4. Cornelissen G, Halberg E, Halberg F, Halberg J, Sampson M, 15. Motohashi Y, Reinberg A, Levi F, Nougier J, Benoit 0, roret Hillman D, Nelson W, Sanchez de la Pena S, Wu J, Delmore J, Bourdeleau P. Axillary temperature: A circadian marker P, Marques N, Marques MD, Fernandez JR. Hennida RC, rhythm for shift workers. Ergonomics 1987; 30: 1235-1247. Guillaume F. Carandente F. Chronobiology: a Frontier in biology and medicine. Chronobiologia 1989; 16: 383-408. 16. Bicakova-Rocher A, Gorceix A. Reinberg A. Possible circadian rhythms alterations in cenain healthy human adults (effects .5. Levi F, Canon C, Depres-Brummer P, Adam R, Bourin P, of placebo). In : "Night and shift-work. Biological and social Pati AK, rlorentin I, Misset JL, Bismuth H. 'lhe rhythmic aspects". Reinberg A, Vieux N, Andlauer P, eds. Pergamon organization of the immune network : implications for Press. Oxford, 1981; 297-310. the chronophamacologic dclivery of inlcrferons, interleukins and cyclosporin. Adv Drug Delivery Reviews 1992; 9: 17. Bicakova-Rocher A, Gorceix A, Nicolai A. Circadian and 85-112. ultradian rhythm period alteration in apparently healthy subjects with and without placebo. Ann Rev Chronophamacol 1984; 6. Pati AK. Jellag, shiflworkers and chronotherapy. Biology 1: 169-171. Education 1993 (in press). 18. Hildebrandt G. Outline of chronohygiene. Chronobiologia 1976; 7. Ostberg O. Circadian rhythms of food intake and oral 3: 113-127. temperature in "morning" and "evening" groups of individuals. Ergonomics 1973; 16: 203-209. 19. Moore-Ede MC, Lydic R. Cuisler CA, Tepper B, Fyller CA. Characterization of separate circadian oscillators driving rest­ 8. Gupta S. Circadian time structure in shift workers and diurnal activity and body temperature rhythms. Sleep Res 1980; 9: healthy human subjects. Ph. D. Thesis, Pt. Ravishanlwr Shukla 275. University, Raipur. India. 1992. 20. Monk TH, Leng VC, Folkard S. Weitzman ED. Circadian 9. Hildebrandt G, Stratmann I. Circadian system response to rhythms in subjective alertness and core body temperature. night work in relation to the individual circadian phase position. Chronobiologia 1983; 10: 49-55. Int Arch Occup Environ Health 1979; 43: 73-83. 21. Monk TH. Shift work: Determinants of coping ability and 10. Reinberg A, Motohashi Y, Bourdeleau P, Touitou Y, Nouguier areas of application. In : "Trends in chronobiology. Advances J, Nouguier Jeanine, Levi F, Nicolai A. International in the Biosciences". W. Th. JM. Hekkens, G.A. Kerkhof and dsynchronization of circadian rhythms and tolerance of shift­ W. J. Rietveld. eds. Pergamon Press OxfordiNY 1988; 73; work. Chronobiologia 1989; 16: 21-34. 195-207.