Noradrenergic control of circadian rhythms in Cebus albifrons
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Winget, C. M.↗
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Results for “Circadian”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Use of KC-135 parabolic flights to determine if brief changes in the gravity field can influence the phase and/or period of the circadian clock
In February 1994 a total of 10 hampsters flew on two separate KC-135 flights. On one flight, 25 animals experienced 31 parabolas, thus going through 31 cycles of hypergravity (up to about 1.8 G). On the other flight, the animals were exposed to 43 parabolas. fifty additional animals served as ground based controls and were treated in the same fashion as the experimental animals. The profiles of plasma GH, corisol and coricosterone from representative parabolic flight and ground control animals during pre-flight, in-flight, and post-flight conditions are depicted.
Turek, Fred W.↗
Experiment K-7-35: Circadian Rhythms and Temperature Regulation During Spaceflight: Metabolism - Part 2
Energy expenditure can be regarded as the sum of two components; the basal metabolic rate and the energy costs of activity. Weight loss is usually associated with an energy deficit. A negative energy balance exists when energy intake is less that energy utilization. The deficit is made up by tissue catabolism (principally fat, but also some protein). By analyzing food and water intake, urine and fecal output, and changes in body weight, the Skylab investigators reached the unexpected conclusion that energy expenditure during spaceflight was about 5% greater than at 1 G (Leonard, 1983; Rambaut et al., 1977). Possible explanations for the human metabolic responses are an increased workload during spaceflight (Leonard, 1983), or as Rambaut and co-workers (1977) suggested, a progressive decrease in metabolic efficiency. It is likely to be very difficult to distinguish between these two possibilities in man because the activity component may be different during spaceflight than it is the ground. The problem is to measure energy expenditure with efficient precision during spaceflight in a non-invasive manner which will not interfere with other investigations or take an time. The doubly labeled water (DLW) method meets these criteria. The DLW method is the only method available for continuously measuring energy expenditure during spaceflight given the severely restricted conditions in the spaceflight environment. Therefore, this study focuses on the development and use of this procedure on nonhuman primates during spaceflight. Energy expenditure and total body water was determined in two Rhesus monkeys by the doubly labeled water (2H2'80) method. Three determinations were made. Monkey B (#2483) was studied twice, during the flight of COSMOS 2044 and during a follow-up ground control study a month later. A second monkey was studied on the ground only (Monkey D, #782).
Fuller, C. A.↗
Sleep, Circadian Rhythms, and Workload in Spaceflight
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A. P. Mulavara↗
Commercial-Off-The-Shelf (COTS) Lighting Workaround for Maintaining Orion Crew Circadian Entrainment
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Matthew Lindsey↗
An Exploration of the Temporal Dynamics of Circadian Resetting Responses to Short- and Long-Duration Light Exposures: Cross-Species Consistencies and Differences
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Richard E. Kronauer↗
Biochronometry; Proceedings of the Symposium, Friday Harbor, Wash., September 4-6, 1969.
Topics discussed include circadian activity rhythms in birds and man, variation of circadian rhythms in monkeys, resetting of circadian eclosion rhythm in fruitflies, the effectiveness of mathematical models of circadian rhythms, the influence of ac electric fields on circadian rhythms in man, the relation between changes in the metabolic rate and circadian periodicity of the resistance of pocket mice to ionizing radiation, the relation between circadian organization and the photoperiodic time measurement in moths, the circadian rhythm of optic nerve potentials in the isolated eye of the sea hare, phasing of circadian temperature rhythms in the pocket mouse by specific spectral regions, the phase-shifting effect of light on circadian rhymicity in the fruifly, hormonal control of circadian rhythms in the fruitfly, metabolically controlled temperature compensation in the circadian rhythm of algae, and circadian rhythms in the chloroplasts of algae. Individual items are abstracted in this issue.
Menaker, M.↗
On-Line Analysis of Physiologic and Neurobehavioral Variables During Long-Duration Space Missions
The goal of this project is to develop reliable statistical algorithms for on-line analysis of physiologic and neurobehavioral variables monitored during long-duration space missions. Maintenance of physiologic and neurobehavioral homeostasis during long-duration space missions is crucial for ensuring optimal crew performance. If countermeasures are not applied, alterations in homeostasis will occur in nearly all-physiologic systems. During such missions data from most of these systems will be either continually and/or continuously monitored. Therefore, if these data can be analyzed as they are acquired and the status of these systems can be continually assessed, then once alterations are detected, appropriate countermeasures can be applied to correct them. One of the most important physiologic systems in which to maintain homeostasis during long-duration missions is the circadian system. To detect and treat alterations in circadian physiology during long duration space missions requires development of: 1) a ground-based protocol to assess the status of the circadian system under the light-dark environment in which crews in space will typically work; and 2) appropriate statistical methods to make this assessment. The protocol in Project 1, Circadian Entrainment, Sleep-Wake Regulation and Neurobehavioral will study human volunteers under the simulated light-dark environment of long-duration space missions. Therefore, we propose to develop statistical models to characterize in near real time circadian and neurobehavioral physiology under these conditions. The specific aims of this project are to test the hypotheses that: 1) Dynamic statistical methods based on the Kronauer model of the human circadian system can be developed to estimate circadian phase, period, amplitude from core-temperature data collected under simulated light- dark conditions of long-duration space missions. 2) Analytic formulae and numerical algorithms can be developed to compute the error in the estimates of circadian phase, period and amplitude determined from the data in Specific Aim 1. 3) Statistical models can detect reliably in near real- time (daily) significant alternations in the circadian physiology of individual subjects by analyzing the circadian and neurobehavioral data collected in Project 1. 4) Criteria can be developed using the Kronauer model and the recently developed Jewett model of cognitive -performance and subjective alertness to define altered circadian and neurobehavioral physiology and to set conditions for immediate administration of countermeasures.
Brown, Emery N.↗
Photons, clocks, and consciousness
Light profoundly impacts human consciousness through the stimulation of the visual system and powerfully regulates the human circadian system, which, in turn, has a broad regulatory impact on virtually all tissues in the body. For more than 25 years, the techniques of action spectroscopy have yielded insights into the wavelength sensitivity of circadian input in humans and other mammalian species. The seminal discovery of melanopsin, the photopigment in intrinsically photosensitive retinal ganglion cells, has provided a significant turning point for understanding human circadian phototransduction. Action spectra in humans show that the peak wavelength sensitivity for this newly discovered sensory system is within the blue portion of the spectrum. This is fundamentally different from the three-cone photopic visual system, as well as the individual rod and cone photoreceptor peaks. Studies on rodents, nonhuman primates, and humans indicate that despite having a different wavelength fingerprint, these classic visual photoreceptors still provide an element of input to the circadian system. These findings open the door to innovations in light therapy for circadian and affective disorders, as well as possible architectural light applications.
Review↗
Research on the Effects of Fatigue within the Corporate/Business Aircraft Environment
In 1980, responding to a Congressional request, NASA Ames Research Center created a program to examine whether 'there is a safety problem of uncertain magnitude, due to transmeridian flying and a potential problem due to fatigue in association with various factors found in air transport operations.' The NASA Ames Fatigue/Jet Lag Program was created to collect systematic, scientific information on fatigue, sleep, circadian rhythms, and performance in flight operations. Three Program goals were established and continue to guide research efforts to: (1) determine the extent of fatigue, sleep loss, and circadian disruption in flight operations; (2) determine the impact of these factors on flight crew performance; (3) develop and evaluate countermeasures to mitigate the adverse effects of these factors and maximize flight crew performance and alertness. Since 1980, studies have been conducted in a variety of aviation environments, in controlled laboratory environments, as well as in a full-mission flight simulation. Early studies included investigations of short-haul, long-haul, and overnight cargo flight crews. In 1991, the name of the program was changed to the Fatigue Countermeasures Program to provide a greater emphasis on the development and evaluation of countermeasures. More recent work has examined the effects of planned cockpit rest as an operational countermeasure and provided analyses of the pertinent sleep/duty factors preceding an aviation accident at Guantanamo Bay, Cuba. The Short-Haul study examined the extent of sleep loss, circadian disruption, and fatigue engendered by flying commercial short-haul air transport operations (flight legs less than eight hours). This was one of the first field studies conducted by the NASA program and provided unique insight into the physiological and subjective effects of flying commercial short-haul operations. It demonstrated that a range of measures could be obtained in an operational environment without disturbing the regular performance of duties. The Long-Haul study examined how long-haul flight crews organized their sleep during a variety of international trip patterns and examined how duty requirements, local time, and the circadian system affected the timing, duration, and quality of sleep. Duty requirements and local time can be viewed as external/environmental constraints on time available for sleep, while the internal circadian system is a major physiological modulator of sleep duration and quality. The Overnight Cargo study documented the psychophysiological effects of flying overnight cargo operations. The data collected clearly demonstrated that overnight cargo operations, like other night work, involve physiological disruption not found in comparable daytime operations.
Neri, David F.↗
The mammalian retina as a clock
Many physiological, cellular, and biochemical parameters in the retina of vertebrates show daily rhythms that, in many cases, also persist under constant conditions. This demonstrates that they are driven by a circadian pacemaker. The presence of an autonomous circadian clock in the retina of vertebrates was first demonstrated in Xenopus laevis and then, several years later, in mammals. In X. laevis and in chicken, the retinal circadian pacemaker has been localized in the photoreceptor layer, whereas in mammals, such information is not yet available. Recent advances in molecular techniques have led to the identification of a group of genes that are believed to constitute the molecular core of the circadian clock. These genes are expressed in the retina, although with a slightly different 24-h profile from that observed in the central circadian pacemaker. This result suggests that some difference (at the molecular level) may exist between the retinal clock and the clock located in the suprachiasmatic nuclei of hypothalamus. The present review will focus on the current knowledge of the retinal rhythmicity and the mechanisms responsible for its control.
Review Literature↗
Identification of Cardiometabolic Vulnerabilities Caused by Effects of Synergistic Stressors that are Commonly Encountered During Space Missions
Microgravity is a physiologically challenging state even when at rest. Astronauts experience additional physical and mental stresses, such as prolonged exertion, sleep loss and circadian misalignment, that could impact cardiovascular function. The main goals of this four year NASA project are to characterize the independent and synergistic effects on cardiovascular and immune function of: (1) circadian misalignment; (2) sleep loss; and (3) varied physical and mental stressors, mimicking some of the synergistic stressors experienced by astronauts. Sixteen healthy volunteers, aged 35-55 years, will be studied with standardized behavioral stressors occurring across all circadian phases, both with and without accruing sleep loss, achieved via two 11-day "forced desynchrony" protocols performed in each subject (randomized, within-subject design), where wake periods are advanced 4-h each "day" (i.e. recurring 20-h "days"). One protocol permits 8.33 h sleep opportunity per 20-h "day" (=10 h sleep per 24-h), and the other permits 5 h sleep per 20-h "day" (=6 h sleep per 24-h; matching the reported sleep duration of astronauts). In both protocols, subjects will perform a standardized stress battery including a cognitively challenging task; bicycle exercise, and passive 60deg head up tilt. Outcome variables include blood pressure, heart rate, arrhythmia frequency, cardiac vagal tone (from heart rate variability), sympathetic activity (catecholamines), and endothelial function. Additional measures of cardiac function (echocardiography), responses to a passive 80deg head up tilt, maximal oxygen uptake, and immune function will be assessed at the beginning and at the end of each protocol (i.e., without and with sleep loss, and before and after circadian misalignment). We hope to identify the relative impact on cardiovascular risk markers of varied behavioural stressors while subjects experience circadian misalignment and sleep loss, mimicking some of the synergistic stressors experienced by astronauts. Supported by NASANNX1 OAR 1 OG.
Ruger, M.↗
Validating and Verifying Biomathematical Models of Human Fatigue
Airline pilots experience acute and chronic sleep deprivation, sleep inertia, and circadian desynchrony due to the need to schedule flight operations around the clock. This sleep loss and circadian desynchrony gives rise to cognitive impairments, reduced vigilance and inconsistent performance. Several biomathematical models, based principally on patterns observed in circadian rhythms and homeostatic drive, have been developed to predict a pilots levels of fatigue or alertness. These models allow for the Federal Aviation Administration (FAA) and commercial airlines to make decisions about pilot capabilities and flight schedules. Although these models have been validated in a laboratory setting, they have not been thoroughly tested in operational environments where uncontrolled factors, such as environmental sleep disrupters, caffeine use and napping, may impact actual pilot alertness and performance. We will compare the predictions of three prominent biomathematical fatigue models (McCauley Model, Harvard Model, and the privately-sold SAFTE-FAST Model) to actual measures of alertness and performance. We collected sleep logs, movement and light recordings, psychomotor vigilance task (PVT), and urinary melatonin (a marker of circadian phase) from 44 pilots in a short-haul commercial airline over one month. We will statistically compare with the model predictions to lapses on the PVT and circadian phase. We will calculate the sensitivity and specificity of each model prediction under different scheduling conditions. Our findings will aid operational decision-makers in determining the reliability of each model under real-world scheduling situations.
fatigue↗
Sleeping on Mars: A Hidden Challenge for Human Space Exploration
The purpose of this talk is to provide a general public audience with basic information about what it is like to sleep in space. Dr. Flynn-Evans will begin by highlighting how sleep is different in movies and science fiction compared to real life. She will next cover basic information about sleep and circadian rhythms, including how sleep works on earth. She will explain how people have circadian rhythms of different lengths and how the circadian clock has to be re-set each day. She will also describe how jet-lag works as an example of what happens during circadian misalignment. Dr. Flynn-Evans will also describe how sleep is different in space and will highlight the challenges that astronauts face in low-earth orbit. She will discuss how astronauts have a shorter sleep duration in space relative to on the ground and how their schedules can shift due to operational constraints. She will also describe how these issues affect alertness and performance. She will then discuss how sleep and scheduling may be different on a long-duration mission to Mars. She will discuss the differences in light and day length on earth and mars and illustrate how those differences pose significant challenges to sleep and circadian rhythms.
Flynn-Evans, Erin↗
Sleeping in Space: An Unexpected Challenge for Future Mars Explorers
This talk will serve as the keynote address for a research symposium being held at Washington State University. The purpose of the talk is to provide researchers and students at WSU with an overview about what it is like to sleep in space. Dr. Flynn-Evans will begin by highlighting how sleep is different in movies and science fiction compared to real life. She will next cover basic information about sleep and circadian rhythms, including how sleep works on earth. She will explain how people have circadian rhythms of different lengths and how the circadian clock has to be re-set each day. She will also describe how jet-lag works as an example of what happens during circadian misalignment. Dr. Flynn-Evans will also describe how sleep is different in space and will highlight the challenges that astronauts face in low-earth orbit. She will discuss how astronauts have a shorter sleep duration in space relative to on the ground and how their schedules can shift due to operational constraints. She will also describe how these issues affect alertness and performance. She will then discuss how sleep and scheduling may be different on a long-duration mission to Mars. She will discuss the differences in light and day length on earth and mars and illustrate how those differences pose significant challenges to sleep and circadian rhythms.
Flynn-Evans, Erin↗
A phase response curve to single bright light pulses in human subjects
The circadian pacemaker is differentially sensitive to the resetting effects of retinal light exposure, depending upon the circadian phase at which the light exposure occurs. Previously reported human phase response curves (PRCs) to single bright light exposures have employed small sample sizes, and were often based on relatively imprecise estimates of circadian phase and phase resetting. In the present study, 21 healthy, entrained subjects underwent pre- and post-stimulus constant routines (CRs) in dim light (approximately 2-7 lx) with maintained wakefulness in a semi-recumbent posture. The 6.7 h bright light exposure stimulus consisted of alternating 6 min fixed gaze (approximately 10 000 lx) and free gaze (approximately 5000-9000 lx) exposures. Light exposures were scheduled across the circadian cycle in different subjects so as to derive a PRC. Plasma melatonin was used to determine the phase of the onset, offset, and midpoint of the melatonin profiles during the CRs. Phase shifts were calculated as the difference in phase between the pre- and post-stimulus CRs. The resultant PRC of the midpoint of the melatonin rhythm revealed a characteristic type 1 PRC with a significant peak-to-trough amplitude of 5.02 h. Phase delays occurred when the light stimulus was centred prior to the critical phase at the core body temperature minimum, phase advances occurred when the light stimulus was centred after the critical phase, and no phase shift occurred at the critical phase. During the subjective day, no prolonged 'dead zone' of photic insensitivity was apparent. Phase shifts derived using the melatonin onsets showed larger magnitudes than those derived from the melatonin offsets. These data provide a comprehensive characterization of the human PRC under highly controlled laboratory conditions.
Randomized Controlled Trial↗
Relationship between alertness, performance, and body temperature in humans
Body temperature has been reported to influence human performance. Performance is reported to be better when body temperature is high/near its circadian peak and worse when body temperature is low/near its circadian minimum. We assessed whether this relationship between performance and body temperature reflects the regulation of both the internal biological timekeeping system and/or the influence of body temperature on performance independent of circadian phase. Fourteen subjects participated in a forced desynchrony protocol allowing assessment of the relationship between body temperature and performance while controlling for circadian phase and hours awake. Most neurobehavioral measures varied as a function of internal biological time and duration of wakefulness. A number of performance measures were better when body temperature was elevated, including working memory, subjective alertness, visual attention, and the slowest 10% of reaction times. These findings demonstrate that an increased body temperature, associated with and independent of internal biological time, is correlated with improved performance and alertness. These results support the hypothesis that body temperature modulates neurobehavioral function in humans.
Non-NASA Center↗