Phase-advance shifts of human circadian pacemaker are accelerated by daytime physical exercise

2001 ◽  
Vol 281 (1) ◽  
pp. R197-R205 ◽  
Author(s):  
Toshihiko Miyazaki ◽  
Satoko Hashimoto ◽  
Satoru Masubuchi ◽  
Sato Honma ◽  
Ken-Ichi Honma
Keyword(s):  
Physical Exercise ◽  
Single Pulse ◽  
Time Of Day ◽  
Phase Advance ◽  
Circadian Pacemaker ◽  
Light Conditions ◽  
Melatonin Rhythm ◽  
Dim Light ◽  
The Difference ◽  
Isolation Facility

Effects of forced sleep-wake schedules with and without physical exercise were examined on the human circadian pacemaker under dim light conditions. Subjects spent 15 days in an isolation facility separately without knowing the time of day and followed a forced sleep-wake schedule of a 23 h 40-min period for 12 cycles, and physical exercise was imposed twice per waking period for 2 h each with bicycle- or rowing-type ergometers. As a result, plasma melatonin rhythm was significantly phase advanced with physical exercise, whereas it was not changed without exercise. The difference in phase was already significant 6 days after the start of exercise. The amplitude of melatonin rhythm was not affected. A single pulse of physical exercise in the afternoon or at midnight significantly phase delayed the melatonin rhythms when compared with the prepulse phase, but the amount of phase shift was not different from that observed in the sedentary controls. These findings indicate that physical exercise accelerates phase-advance shifts of the human circadian pacemaker associated with the forced sleep-wake schedule.

Plasma melatonin concentrations in hibernating marmots: absence of a plasma melatonin rhythm

1984 ◽  
Vol 247 (6) ◽  
pp. R1062-R1066 ◽  
Author(s):  
G. L. Florant ◽  
M. L. Rivera ◽  
A. K. Lawrence ◽  
L. Tamarkin
Keyword(s):  
Time Of Day ◽  
Tissue Temperature ◽  
Constant Darkness ◽  
Circadian Pacemaker ◽  
Melatonin Secretion ◽  
Melatonin Concentration ◽  
Ambient Temperatures ◽  
Melatonin Rhythm ◽  
Plasma Melatonin ◽  
Deep Hibernation

Plasma melatonin concentrations were measured throughout bouts of hibernation in marmots maintained in a short photoperiod (light-dark 8:16) and ambient temperature of 5 or 15 degrees C. Melatonin concentration was also measured in two animals maintained in constant darkness. As an animal entered hibernation, plasma melatonin concentrations dropped to basal levels when body temperature reached 25 degrees C, and they remained low until arousal. During deep hibernation plasma melatonin values did not vary significantly (P greater than 0.05) with respect to time of day or different ambient temperatures. With nocturnal arousal plasma melatonin levels were similar to euthermic night values. Lack of a plasma melatonin rhythm during hibernation suggests that the pineal gland is not temperature compensated during hibernation, and due to the low tissue temperature of the pineal the circadian pacemaker driving melatonin secretion is incapable of stimulating a rhythm.

scholarly journals Driver Response to a Dynamic Speed Feedback Sign on Freeway Exit Ramps Based on Sign Location, Interchange Type, and Time of Day

2021 ◽  
pp. 036119812110152
Author(s):  
Md Shakir Mahmud ◽  
Matthew Motz ◽  
Travis Holpuch ◽  
Jordan Hankin ◽  
Anthony J. Ingle ◽  
...  
Keyword(s):  
Time Of Day ◽  
Light Conditions ◽  
Driver Response ◽  
Beneficial Effects ◽  
Passenger Vehicles ◽  
System Versus ◽  
Feedback Sign ◽  
Speed Selection ◽  
Peak Versus ◽  
Horizontal Curvature

A series of field evaluations was performed at three freeway interchange ramps in Michigan that possessed significant horizontal curvature to assess the impacts of a dynamic speed feedback sign (DSFS) on driver speed selection and brake response while approaching and entering the ramp curve. A DSFS with a 15 in. full-matrix display was temporarily installed at each of the three exit ramp locations. The sign was programmed to display the same feedback message at each location, which included the speed number for all approaching vehicles, which alternated with a “Slow Down” message for vehicles approaching above 40 mph. The effectiveness of the feedback sign was tested across various sign locations (at the point of curvature versus 350 ft upstream), interchange types (system versus service), time of day (peak versus off-peak), light conditions (daylight versus darkness), and vehicle types (passenger vehicles versus trucks). Compared with the pre-DSFS site condition, the DSFS reduced curve entry speeds and improved brake response at two of the three ramp locations. In general, the greatest beneficial effects on driver behavior were achieved when the DSFS was positioned at the point of curvature, during which curve entry speeds were reduced by approximately 2 mph. These findings were consistent between the system interchanges and service interchanges, and across all vehicle types. The DSFS was also found to be most effective during daytime off-peak periods compared with peak periods and at night. Further evaluation of DSFS at additional ramp locations, and considering an expanded set of conditions, is recommended.

Physical exercise accelerates reentrainment of human sleep-wake cycle but not of plasma melatonin rhythm to 8-h phase-advanced sleep schedule

2010 ◽  
Vol 298 (3) ◽  
pp. R681-R691 ◽  
Author(s):  
Yujiro Yamanaka ◽  
Satoko Hashimoto ◽  
Yusuke Tanahashi ◽  
Shin-ya Nishide ◽  
Sato Honma ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Physical Exercise ◽  
Sleep Onset ◽  
Exercise Group ◽  
Control Group ◽  
Temporal Isolation ◽  
Melatonin Rhythm ◽  
Plasma Melatonin ◽  
Shift Schedule ◽  
Sleep Schedule

Effects of timed physical exercise were examined on the reentrainment of sleep-wake cycle and circadian rhythms to an 8-h phase-advanced sleep schedule. Seventeen male adults spent 12 days in a temporal isolation facility with dim light conditions (<10 lux). The sleep schedule was phase-advanced by 8 h from their habitual sleep times for 4 days, which was followed by a free-run session for 6 days, during which the subjects were deprived of time cues. During the shift schedule, the exercise group ( n = 9) performed physical exercise with a bicycle ergometer in the early and middle waking period for 2 h each. The control group ( n = 8) sat on a chair at those times. Their sleep-wake cycles were monitored every day by polysomnography and/or weight sensor equipped with a bed. The circadian rhythm in plasma melatonin was measured on the baseline day before phase shift: on the 4th day of shift schedule and the 5th day of free-run. As a result, the sleep-onset on the first day of free-run in the exercise group was significantly phase-advanced from that in the control and from the baseline. On the other hand, the circadian melatonin rhythm was significantly phase-delayed in the both groups, showing internal desynchronization of the circadian rhythms. The sleep-wake cycle resynchronized to the melatonin rhythm by either phase-advance or phase-delay shifts in the free-run session. These findings indicate that the reentrainment of the sleep-wake cycle to a phase-advanced schedule occurs independent of the circadian pacemaker and is accelerated by timed physical exercise.

scholarly journals Effects of light and ethylene on endogenous hormones and development of Catasetum fimbriatum (Orchidaceae)

2006 ◽  
Vol 18 (3) ◽  
pp. 359-365 ◽  
Author(s):  
Rogério M. Suzuki ◽  
Gilberto B. Kerbauy
Keyword(s):  
Leaf Growth ◽  
Shoot Elongation ◽  
Zeatin Riboside ◽  
Endogenous Hormones ◽  
Light Conditions ◽  
Active Growth ◽  
Dark Light ◽  
The Difference ◽  
Catasetum Fimbriatum ◽  
Indole 3 Acetic Acid

This study attempted to clarify the effects of dark, light and ethylene on plant growth and endogenous levels of indole-3-acetic acid (IAA), cytokinins and abscisic acid in Catasetum fimbriatum. Dark-incubation fully inhibited root and pseudobulb formation as well as leaf growth, but favored shoot elongation. The results of continuous and active growth in dark-incubated shoots (stolons) were induced by strong apical meristem sink activity and by the significantly increased levels of cytokinins in shoots. In fact, shoot length, cytokinin and IAA levels in dark-incubated shoots were about twice as great as for those grown under light conditions. Moreover, the total cytokinin level in shoots of C. fimbriatum under light conditions without ethylene was significantly higher than that found in roots. High levels of cytokinins in dark-grown stolons may be closely related to the absence of roots in C. fimbriatum. Under light conditions, the increased IAA level in shoots is mediated by ethylene. However, ethylene caused a significant increase of cytokinins in roots of light-treated plants, which may be involved in the retardation of root growth. Since the difference of cytokinins in shoots between ethylene-treated and non-treated plants under light conditions is small, it is concluded that the marked inhibition of leaf growth in ethylene-treated plants can be attributed to ethylene. Zeatin and zeatin riboside are the major cytokinins in C. fimbriatum regardless of the light conditions, ethylene treatment or organ types.

scholarly journals Investigation of monthly variations in the efficiencies of photovoltaics due to sunrise and sunset times

2020 ◽  
Vol 18 (1) ◽  
pp. 310
Author(s):  
Armstrong O. Njok ◽  
Julie C. Ogbulezie ◽  
Manoj Kumar Panjwani ◽  
Raja Masood Larik
Keyword(s):  
Relative Humidity ◽  
Solar Energy ◽  
Electrical Energy ◽  
Time Of Day ◽  
Peak Efficiency ◽  
Pv Module ◽  
Average Relative Humidity ◽  
The Difference ◽  
Monthly Variations ◽  
Different Levels

<p>The effect of time of day and month on the efficient conversion of solar energy to electrical energy using a polycrystalline (PV) module in calabar was studied. A KT-908 precision digital hygrometer and thermometer, and a M890C+ digital multimeter were used in the process. Results obtained shows that photovoltaic produce different levels of peak efficiencies at different times of the day for different months due to the difference in sunrise and sunset times for the months. The results also indicated that photovoltaics will be more efficient in months with low average relative humidity couple with low panel temperature. A peak efficiency of 77% at 12:30 in the month of April was observed before dropping to 73% at 12:00 in the month of May, indicating that there might be further drop in efficiency as we proceed further into the year. Results also show that photovoltaics are more efficient before noon in the month of May than in April while the reverse will be observed in the afternoon. </p>

scholarly journals Road lighting density and brightness linked with increased cycling rates after-dark

2020 ◽  
Author(s):  
Jim Uttley ◽  
Steve Fotios ◽  
Robin Lovelace
Keyword(s):  
Negative Impact ◽  
Time Of Day ◽  
Aerial Images ◽  
Minimal Amount ◽  
Night Time ◽  
Road Lighting ◽  
International Policies ◽  
Relative Brightness ◽  
Two Measures ◽  
The Difference

Cycling has a range of benefits as is recognised by national and international policies aiming to increase cycling rates. Darkness acts as a barrier to people cycling, with fewer people cycling after-dark when seasonal and time-of-day factors are accounted for. This paper explores whether road lighting can reduce the negative impact of darkness on cycling rates. Changes in cycling rates between daylight and after-dark were quantified for 48 locations in Birmingham, United Kingdom, by calculating an odds ratio. These odds ratios were compared against two measures of road lighting at each location: 1) Density of road lighting lanterns; 2) Relative brightness as estimated from night-time aerial images. Locations with no road lighting showed a significantly greater reduction in cycling after-dark compared with locations that had some lighting. A nonlinear relationship was found between relative brightness at a location at night and the reduction in cyclists after-dark. Small initial increases in brightness resulted in large reductions in the difference between cyclist numbers in daylight and after-dark, but this effect reached a plateau as brightness increased. These results suggest only a minimal amount of lighting may be sufficient to promote cycling after-dark.

scholarly journals HUMAN BODY’S HEALTH FUNCTION IMPROVEMENT BY VARIOUS WHOLE-BODY SPORTS EXERCISES

2021 ◽  
Vol 27 (3) ◽  
pp. 270-273
Author(s):  
Ji Hu ◽  
Jicheng Yang
Keyword(s):  
Physical Exercise ◽  
Human Health ◽  
Tai Chi ◽  
Exercise Group ◽  
Whole Body ◽  
Group Health ◽  
Traditional Health ◽  
Physical Exercises ◽  
The Difference ◽  
Health Function

ABSTRACT Introduction Studies have shown that physical exercise is beneficial to people’s overall physical and mental health, but few research reports on the effects of different physical exercises on people’s human health. Object The paper explores the difference in human health function between people who adhere to traditional health sports and those who rarely exercise and provide a scientific basis for applying and promoting traditional health sports in TCM “prevention of disease”. Methods The paper surveyed 526 people who regularly participate in physical exercises and rarely exercise. The exercise items are divided into Tai Chi/Tai Chi sword group, Health Qigong Baduanjin group, Health Qigong Wuqinxi group, and Health Qigong Yijin group. Warp group, walking/jogging group. Results There are differences in the mental indicators of the people in different exercise groups. The overall average percentage levels of and NK cells in each exercise group and the tiny exercise group are different, and the difference is statistically significant (P<0.05). Conclusions Persisting in physical exercise is beneficial to the balance of health and function of the population. Level of evidence II; Therapeutic studies - investigation of treatment results.

High salt mimics effects of light pulses on circadian pacemaker in cultured chick pineal cells

1991 ◽  
Vol 260 (4) ◽  
pp. R769-R776 ◽  
Author(s):  
M. Zatz ◽  
H. M. Wang
Keyword(s):  
Dominant Role ◽  
Red Light ◽  
Phase Shifts ◽  
Membrane Depolarization ◽  
Cell Swelling ◽  
Circadian Pacemaker ◽  
Cell Shrinkage ◽  
Phase Dependence ◽  
Melatonin Rhythm ◽  
High Concentrations

Chick pineal cells in static culture display a persistent photosensitive circadian rhythm of melatonin production and release. Pulses of white light or darkness, in otherwise constant red light, induce phase shifts in subsequent cycles whose magnitude and direction depend on the phase at which the pusle is given. Such "phase-dependent phase shifts" are mediated by effects on the underlying pacemaker. We reported previously that inhibiting the Na+-K+-adenosinetriphosphatase with ouabain evokes phase shifts with the same phase dependence as those induced by pulses of darkness. Two of the consequences of inhibiting the Na+ pump are membrane depolarization and cell swelling. To test the relevance of these effects and to distinguish between them, we exposed chick pineal cells to pulses of high concentrations of added KCl, which should cause both membrane depolarization and cell shrinkage. We also compared the effects of added NaCl, sodium gluconate, and mannitol, which should cause cell shrinkage without comparable depolarization. Each of these hypertonic solutions induced phase shifts in the melatonin rhythm with the same phase dependence as those caused by pulses of light rather than those caused by ouabain or darkness. These results argue strongly against a dominant role for changes in membrane potential in phase shifting the melatonin rhythm. Rather, they suggest that cell swelling may mediate the darklike effects of ouabain on the circadian pacemaker in chick pineal cells and indicate that cell shrinkage mimics the effects of light.

scholarly journals Physical activity during pregnancy and its influence on delivery time: a randomized clinical trial

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6370 ◽  
Author(s):  
Raquel Rodríguez-Blanque ◽  
Juan Carlos Sánchez-García ◽  
Antonio Manuel Sánchez-López ◽  
María José Aguilar-Cordero
Keyword(s):  
Physical Exercise ◽  
Pregnant Women ◽  
Intervention Program ◽  
Total Duration ◽  
Perinatal Outcomes ◽  
Exercise Group ◽  
University Hospital ◽  
Control Group ◽  
Beneficial Effects ◽  
The Difference

Introduction During pregnancy, women often change their lifestyle for fear of harmful effects on the child or themselves. In this respect, many women reduce the amount of physical exercise they take, despite its beneficial effects. Objective To determine the duration of labor in pregnant women who completed a program of moderate physical exercise in water and subsequently presented eutocic birth. Methods A randomized trial was performed with 140 healthy pregnant women, divided into an exercise group (EG) (n = 70) and a control group (CG) (n = 70). The women who composed the study population were recruited at 12 weeks of gestation. The intervention program, termed SWEP (Study of Water Exercise during Pregnancy) began in week 20 of gestation and ended in week 37. Perinatal outcomes were determined by examining the corresponding partographs, recorded by the Maternity Service at the Granada University Hospital Complex. Results The intervention phase of the study took place from June through October 2016, with the 120 women finally included in EG and CG (60 in each group). At term, 63% of the women in EG and 56% of those in CG had a eutocic birth. The average total duration of labor was 389.33 ± 216.18 min for the women in EG and 561.30 ± 199.94 min for those in CG, a difference of approximately three hours (p < 0.001). Conclusions The women who exercised in water during their pregnancy presented a shorter duration of labor than those who did not. The difference was especially marked with respect to the duration of the first and second stages of labor.

scholarly journals A late wake time phase delays the human dim light melatonin rhythm

2006 ◽  
Vol 395 (3) ◽  
pp. 191-195 ◽  
Author(s):  
Helen J. Burgess ◽  
Charmane I. Eastman
Keyword(s):  
Wake Time ◽  
Melatonin Rhythm ◽  
Dim Light
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