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...AS). Visual vigilance/attention was measured with the Psychomotor Vigilance Task (PVT), for which we assessed the number of lapses, median reaction time, and the fastest and slowest 10% reaction time =-=(19)-=-. These tests were selected because they are known to vary with the circadian rhythm of body temperature and to be sensitive to sleep loss (9, 18, 19, 54). Data analysis. The intrinsic circadian perio...

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...nt of the human circadian clock under these dim light conditions, i.e., the circadian clock cannot adapt to the 28-h day length and instead it continues to oscillate at its near-24-h intrinsic period =-=(15, 53)-=-. Body temperature was measured every minute by means of a rectal thermistor (Yellow Springs Instruments, Yellow Springs, OH), except during showers and bowel movements, and room temperature was maint...

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...43, 44). Homeostatic and circadian mechanisms influence cutaneous vasodilatation, peripheral vasoconstriction, and basal metabolism, all of which change the rate at which body heat is lost and gained =-=(36)-=-. The circadian peak-to-trough range of body temperature, when examined under controlled environmental conditions (e.g., constant ambient temperature, constant dim light, supine posture, restricted ac...

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...ed by decreasing body temperature below normal (3, 23–26, 46, 48). Low performance associated with low body temperature has also been reported in studies of shift work and continuous night operations =-=(10, 13, 17, 33)-=-. In forced desynchrony studies, which experimentally separate circadian and sleep-wake homeostatic influences on neurobehavioral function, it has also been reported that performance tends to be lowes...

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...and bright light exposure also influenced neurobehavioral performance. For example, melatonin administration during the biological day decreased body temperature and reduced performance and alertness =-=(20, 27, 35, 45)-=-. Exposure to bright light and/or the ingestion of caffeine increased nocturnal body temperature level and improved performance when examined under controlled constant-routine conditions (5, 22, 50, 5...

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...t controlled for changes in wakefulness-sleep state (37). Yet, even under controlled conditions, the amplitude of the body temperature rhythm is reported to be influenced by other factors such as age =-=(8, 11, 16, 21)-=- and menstrual cycle phase (6, 49). It has long been recognized that there exists a positive relationship between daily rhythms of body temperature and neurobehavioral performance and alertness in hum...

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... both the forced period of the imposed sleep-wake cycle and the soughtfor period of the endogenous circadian rhythm, together with their harmonics, using an exact maximum likelihood fitting procedure =-=(7)-=-. This technique is described in detail in Ref. 15. Neurobehavioral performance and alertness data were then averaged into 60-degree (4-h) bins with the phase of the body temperature minimum (Tmin) as...

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...admission, verified by call-in times to a time-stamped voice recorder, sleep logs, and for at least 1 wk by wrist actigraphy (Minimitter, Sun River, OR). On days 35–49 of a 55-day in-patient protocol =-=(53)-=-, participants were scheduled to a forced desynchrony protocol (Fig. 1) for 12 consecutive 28-h days (18.66 h of scheduled wakefulness and 9.33 h of scheduled sleep). Subjects were scheduled to sleep ...

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...and bright light exposure also influenced neurobehavioral performance. For example, melatonin administration during the biological day decreased body temperature and reduced performance and alertness =-=(20, 27, 35, 45)-=-. Exposure to bright light and/or the ingestion of caffeine increased nocturnal body temperature level and improved performance when examined under controlled constant-routine conditions (5, 22, 50, 5...

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...tion time, and the fastest and slowest 10% reaction time (19). These tests were selected because they are known to vary with the circadian rhythm of body temperature and to be sensitive to sleep loss =-=(9, 18, 19, 54)-=-. Data analysis. The intrinsic circadian period of the body temperature rhythm was estimated using a nonorthogonal spectral analysis technique. That is, temperature data were fitted with periodic comp...

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...eep state (37). Yet, even under controlled conditions, the amplitude of the body temperature rhythm is reported to be influenced by other factors such as age (8, 11, 16, 21) and menstrual cycle phase =-=(6, 49)-=-. It has long been recognized that there exists a positive relationship between daily rhythms of body temperature and neurobehavioral performance and alertness in humans (4, 32–34, 38). During total s...

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...ed by decreasing body temperature below normal (3, 23–26, 46, 48). Low performance associated with low body temperature has also been reported in studies of shift work and continuous night operations =-=(10, 13, 17, 33)-=-. In forced desynchrony studies, which experimentally separate circadian and sleep-wake homeostatic influences on neurobehavioral function, it has also been reported that performance tends to be lowes...

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..., 27, 35, 45). Exposure to bright light and/or the ingestion of caffeine increased nocturnal body temperature level and improved performance when examined under controlled constant-routine conditions =-=(5, 22, 50, 51)-=-. While these pharmacological, physiological, and environmental stimuli are likely to affect performance via mechanisms other than body temperature (e.g., blocking of adenosine receptors by caffeine),...

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... brain temperature in mammals within a limited range in response to physiological and environmental conditions, and the suprachiasmatic nuclei regulate the circadian or near24-h rhythm of temperature =-=(28, 43, 44)-=-. Homeostatic and circadian mechanisms influence cutaneous vasodilatation, peripheral vasoconstriction, and basal metabolism, all of which change the rate at which body heat is lost and gained (36). T...

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...ed by decreasing body temperature below normal (3, 23–26, 46, 48). Low performance associated with low body temperature has also been reported in studies of shift work and continuous night operations =-=(10, 13, 17, 33)-=-. In forced desynchrony studies, which experimentally separate circadian and sleep-wake homeostatic influences on neurobehavioral function, it has also been reported that performance tends to be lowes...

Citation Context

...t controlled for changes in wakefulness-sleep state (37). Yet, even under controlled conditions, the amplitude of the body temperature rhythm is reported to be influenced by other factors such as age =-=(8, 11, 16, 21)-=- and menstrual cycle phase (6, 49). It has long been recognized that there exists a positive relationship between daily rhythms of body temperature and neurobehavioral performance and alertness in hum...

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...ian phase; neurobehavioral performance; forced desynchrony; core body temperature CONSIDERABLE EFFORT has been devoted to understanding the relationship between body temperature and human performance =-=(2, 4, 12, 24, 34, 48)-=-. Kleitman (32–34) originally proposed that body temperature was an underlying mechanism regulating performance. “Assuming that the effect of temperature indicates that we are dealing with a chemical ...

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...5.2002. 0363-6119/02 $5.00 Copyright © 2002 the American Physiological Society http://www.ajpregu.orgR1370sby 10.220.33.4 on Septem ber 18, 2016 http://ajpregu.physiology.org/ D ow nloaded from night =-=(5)-=-. The positive relationship between rhythms in performance and body temperature has been verified by studies that have controlled for factors that can influence body temperature and performance, such ...

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...erformance are also consistent with results from studies in which performance was examined during and after extreme body cooling and heating (3, 23–26, 46, 48). For example, Giesbrecht and colleagues =-=(26)-=- immersed participants in cold water that was 8°C for 55–80 min until participants’ body temperature was reduced from 37.0 to 33.0–34.8°C, as measured in the esophagus at heart level. Compared with t...

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...s hypothesis is supported by results from studies using in vitro and in vivo preparations in which it was reported that synaptic function is altered by supraphysiological changes in brain temperature =-=(39, 40, 47)-=- such that higher brain temperatures resulted in faster transmission, whereas lower brain temperature resulted in slower transmission. Brain mechanisms involved in the regulation of body temperature i...

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... function, it has also been reported that performance tends to be lowest during the biological night near to the minimum of the body temperature rhythm regardless of the duration of prior wakefulness =-=(14, 18, 30, 54)-=-. Yet, it has been unclear from prior studies whether performance is directly affected by body temperature or whether both body temperature and performance simply covary with circadian phase. To addre...

Citation Context

...ian phase; neurobehavioral performance; forced desynchrony; core body temperature CONSIDERABLE EFFORT has been devoted to understanding the relationship between body temperature and human performance =-=(2, 4, 12, 24, 34, 48)-=-. Kleitman (32–34) originally proposed that body temperature was an underlying mechanism regulating performance. “Assuming that the effect of temperature indicates that we are dealing with a chemical ...

Citation Context

...eep state (37). Yet, even under controlled conditions, the amplitude of the body temperature rhythm is reported to be influenced by other factors such as age (8, 11, 16, 21) and menstrual cycle phase =-=(6, 49)-=-. It has long been recognized that there exists a positive relationship between daily rhythms of body temperature and neurobehavioral performance and alertness in humans (4, 32–34, 38). During total s...

Citation Context

...t controlled for changes in wakefulness-sleep state (37). Yet, even under controlled conditions, the amplitude of the body temperature rhythm is reported to be influenced by other factors such as age =-=(8, 11, 16, 21)-=- and menstrual cycle phase (6, 49). It has long been recognized that there exists a positive relationship between daily rhythms of body temperature and neurobehavioral performance and alertness in hum...

Citation Context

...s hypothesis is supported by results from studies using in vitro and in vivo preparations in which it was reported that synaptic function is altered by supraphysiological changes in brain temperature =-=(39, 40, 47)-=- such that higher brain temperatures resulted in faster transmission, whereas lower brain temperature resulted in slower transmission. Brain mechanisms involved in the regulation of body temperature i...

Citation Context

...t controlled for changes in wakefulness-sleep state (37). Yet, even under controlled conditions, the amplitude of the body temperature rhythm is reported to be influenced by other factors such as age =-=(8, 11, 16, 21)-=- and menstrual cycle phase (6, 49). It has long been recognized that there exists a positive relationship between daily rhythms of body temperature and neurobehavioral performance and alertness in hum...

Citation Context

...and bright light exposure also influenced neurobehavioral performance. For example, melatonin administration during the biological day decreased body temperature and reduced performance and alertness =-=(20, 27, 35, 45)-=-. Exposure to bright light and/or the ingestion of caffeine increased nocturnal body temperature level and improved performance when examined under controlled constant-routine conditions (5, 22, 50, 5...

Citation Context

... brain temperature in mammals within a limited range in response to physiological and environmental conditions, and the suprachiasmatic nuclei regulate the circadian or near24-h rhythm of temperature =-=(28, 43, 44)-=-. Homeostatic and circadian mechanisms influence cutaneous vasodilatation, peripheral vasoconstriction, and basal metabolism, all of which change the rate at which body heat is lost and gained (36). T...

Citation Context

...ian phase; neurobehavioral performance; forced desynchrony; core body temperature CONSIDERABLE EFFORT has been devoted to understanding the relationship between body temperature and human performance =-=(2, 4, 12, 24, 34, 48)-=-. Kleitman (32–34) originally proposed that body temperature was an underlying mechanism regulating performance. “Assuming that the effect of temperature indicates that we are dealing with a chemical ...

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... body temperature when examined in greater detail, specifically when the slowest reaction times are examined. In other related studies, body temperature was raised and changes in performance reported =-=(1, 2, 24, 29, 48)-=-. Wilkinson and colleagues (48) raised subjects’ body temperature from the normal temperature of 37.0°C, up to 37.3–38.5°C, by exposing subjects to a hot 43°C humid climate. Auditory vigilance perfor...

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...ian phase; neurobehavioral performance; forced desynchrony; core body temperature CONSIDERABLE EFFORT has been devoted to understanding the relationship between body temperature and human performance =-=(2, 4, 12, 24, 34, 48)-=-. Kleitman (32–34) originally proposed that body temperature was an underlying mechanism regulating performance. “Assuming that the effect of temperature indicates that we are dealing with a chemical ...

Citation Context

... function, it has also been reported that performance tends to be lowest during the biological night near to the minimum of the body temperature rhythm regardless of the duration of prior wakefulness =-=(14, 18, 30, 54)-=-. Yet, it has been unclear from prior studies whether performance is directly affected by body temperature or whether both body temperature and performance simply covary with circadian phase. To addre...

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..., 27, 35, 45). Exposure to bright light and/or the ingestion of caffeine increased nocturnal body temperature level and improved performance when examined under controlled constant-routine conditions =-=(5, 22, 50, 51)-=-. While these pharmacological, physiological, and environmental stimuli are likely to affect performance via mechanisms other than body temperature (e.g., blocking of adenosine receptors by caffeine),...

Citation Context

... function, it has also been reported that performance tends to be lowest during the biological night near to the minimum of the body temperature rhythm regardless of the duration of prior wakefulness =-=(14, 18, 30, 54)-=-. Yet, it has been unclear from prior studies whether performance is directly affected by body temperature or whether both body temperature and performance simply covary with circadian phase. To addre...

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...functions were better when body temperature was high than when it was low. This result in individual subjects is consistent with previous work that did not control for circadian phase and hours awake =-=(23, 24)-=- and is also consistent with the highest vs. lowest group analysis of the current study. The current result showing that body temperature was low during the biological night, increased near habitual w...

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...s reported to vary with the circadian rhythm of body temperature, although the rhythm in brain temperature was not tested in constant conditions that controlled for changes in wakefulness-sleep state =-=(37)-=-. Yet, even under controlled conditions, the amplitude of the body temperature rhythm is reported to be influenced by other factors such as age (8, 11, 16, 21) and menstrual cycle phase (6, 49). It ha...

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..., 27, 35, 45). Exposure to bright light and/or the ingestion of caffeine increased nocturnal body temperature level and improved performance when examined under controlled constant-routine conditions =-=(5, 22, 50, 51)-=-. While these pharmacological, physiological, and environmental stimuli are likely to affect performance via mechanisms other than body temperature (e.g., blocking of adenosine receptors by caffeine),...

Citation Context

...ian phase; neurobehavioral performance; forced desynchrony; core body temperature CONSIDERABLE EFFORT has been devoted to understanding the relationship between body temperature and human performance =-=(2, 4, 12, 24, 34, 48)-=-. Kleitman (32–34) originally proposed that body temperature was an underlying mechanism regulating performance. “Assuming that the effect of temperature indicates that we are dealing with a chemical ...

Citation Context

...ed by decreasing body temperature below normal (3, 23–26, 46, 48). Low performance associated with low body temperature has also been reported in studies of shift work and continuous night operations =-=(10, 13, 17, 33)-=-. In forced desynchrony studies, which experimentally separate circadian and sleep-wake homeostatic influences on neurobehavioral function, it has also been reported that performance tends to be lowes...

Citation Context

...ian phase; neurobehavioral performance; forced desynchrony; core body temperature CONSIDERABLE EFFORT has been devoted to understanding the relationship between body temperature and human performance =-=(2, 4, 12, 24, 34, 48)-=-. Kleitman (32–34) originally proposed that body temperature was an underlying mechanism regulating performance. “Assuming that the effect of temperature indicates that we are dealing with a chemical ...

Citation Context

... brain temperature in mammals within a limited range in response to physiological and environmental conditions, and the suprachiasmatic nuclei regulate the circadian or near24-h rhythm of temperature =-=(28, 43, 44)-=-. Homeostatic and circadian mechanisms influence cutaneous vasodilatation, peripheral vasoconstriction, and basal metabolism, all of which change the rate at which body heat is lost and gained (36). T...

Citation Context

... body temperature when examined in greater detail, specifically when the slowest reaction times are examined. In other related studies, body temperature was raised and changes in performance reported =-=(1, 2, 24, 29, 48)-=-. Wilkinson and colleagues (48) raised subjects’ body temperature from the normal temperature of 37.0°C, up to 37.3–38.5°C, by exposing subjects to a hot 43°C humid climate. Auditory vigilance perfor...

Citation Context

... function, it has also been reported that performance tends to be lowest during the biological night near to the minimum of the body temperature rhythm regardless of the duration of prior wakefulness =-=(14, 18, 30, 54)-=-. Yet, it has been unclear from prior studies whether performance is directly affected by body temperature or whether both body temperature and performance simply covary with circadian phase. To addre...

Citation Context

...s hypothesis is supported by results from studies using in vitro and in vivo preparations in which it was reported that synaptic function is altered by supraphysiological changes in brain temperature =-=(39, 40, 47)-=- such that higher brain temperatures resulted in faster transmission, whereas lower brain temperature resulted in slower transmission. Brain mechanisms involved in the regulation of body temperature i...

Citation Context

...and bright light exposure also influenced neurobehavioral performance. For example, melatonin administration during the biological day decreased body temperature and reduced performance and alertness =-=(20, 27, 35, 45)-=-. Exposure to bright light and/or the ingestion of caffeine increased nocturnal body temperature level and improved performance when examined under controlled constant-routine conditions (5, 22, 50, 5...