Circadian Rhythm Of Rectal Temperature Research Articles

Diurnal rhythms of urine volume and electrolyte excretion in healthy young men under differing intensities of daytime light exposure

In humans, most renal functions, including urine volume and electrolyte excretions, have a circadian rhythm. Light is a strong circadian entrainment factor and daytime-light exposure is known to affect the circadian rhythm of rectal temperature (RT). The effects of daytime-light exposure on the diurnal rhythm of urinary excretion have yet to be clarified. The aim of this study was to clarify whether and how daytime exposure to bright-light affects urinary excretions. Twenty-one healthy men (21–27 years old) participated in a 4-day study involving daytime (08:00–18:00 h) exposure to two light conditions, Dim (< 50 lx) and Bright (~ 2500 lx), in a random order. During the experiment, RT was measured continuously. Urine samples were collected every 3 ~ 4 h. Compared to the Dim condition, under the Bright condition, the RT nadir time was 45 min earlier (p = 0.017) and sodium (Na), chloride (Cl), and uric acid (UA) excretion and urine volumes were greater (all p < 0.001), from 11:00 h to 13:00 h without a difference in total daily urine volume. The present results suggest that daytime bright light exposure can induce a phase shift advance in urine volume and urinary Na, Cl, and UA excretion rhythms.

Circadian rhythms in bed rest: Monitoring core body temperature via heat-flux approach is superior to skin surface temperature

ABSTRACTContinuous recordings of core body temperature (CBT) are a well-established approach in describing circadian rhythms. Given the discomfort of invasive CBT measurement techniques, the use of skin temperature recordings has been proposed as a surrogate. More recently, we proposed a heat-flux approach (the so-called Double Sensor) for monitoring CBT. Studies investigating the reliability of the heat-flux approach over a 24-hour period, as well as comparisons with skin temperature recordings, are however lacking. The first aim of the study was therefore to compare rectal, skin, and heat-flux temperature recordings for monitoring circadian rhythm. In addition, to assess the optimal placement of sensor probes, we also investigated the effect of different anatomical measurement sites, i.e. sensor probes positioned at the forehead vs. the sternum. Data were collected as part of the Berlin BedRest study (BBR2-2) under controlled, standardized, and thermoneutral conditions. 24-hours temperature data of seven healthy males were collected after 50 days of -6° head-down tilt bed-rest. Mean Pearson correlation coefficients indicated a high association between rectal and forehead temperature recordings (r > 0.80 for skin and Double Sensor). In contrast, only a poor to moderate relationship was observed for sensors positioned at the sternum (r = -0.02 and r = 0.52 for skin and Double Sensor, respectively). Cross-correlation analyses further confirmed the feasibility of the forehead as a preferred monitoring site. The phase difference between forehead Double Sensor and rectal recordings was not statistically different from zero (p = 0.313), and was significantly smaller than the phase difference between forehead skin and rectal temperatures (p = 0.016). These findings were substantiated by cosinor analyses, revealing significant differences for mesor, amplitude, and acrophase between rectal and forehead skin temperature recordings, but not between forehead Double Sensor and rectal temperature measurements. Finally, Bland-Altman analysis indicated narrower limits of agreement for rhythm parameters between rectal and Double Sensor measurements compared to between rectal and skin recordings, irrespective of the measurement site (i.e. forehead, sternum). Based on these data we conclude that (1) Double Sensor recordings are significantly superior to skin temperature measurements for non-invasively assessing the circadian rhythm of rectal temperature, and (2) temperature rhythms from the sternum are less reliable than from the forehead. We suggest that forehead Double Sensor recordings may provide a surrogate for rectal temperature in circadian rhythm research, where constant routine protocols are applied. Future studies will be needed to assess the sensor’s ecological validity outside the laboratory under changing environmental and physiological conditions.

Physiological Significance of Cyclic Changes in Room Temperature around Dusk and Dawn for Circadian Rhythms of Core and Skin Temperature, Urinary 6-hydroxymelatonin Sulfate, and Waking Sensation just after Rising

The present study investigated whether room temperature (T(a)) cycles around dusk and dawn could influence the circadian rhythm of rectal temperature (T(core)), urinary 6-hydroxymelatonin sulfate during nocturnal sleep, and subjective assessments of sleep in humans. Six female and two male students served as participants. Two different T(a) conditions, cyclic and constant, were established. Two kinds of room temperature were provided to subjects: cyclic T(a) (gradual decrease from 27 degrees C to 24 degrees C between 1800 and 2200 h and gradual increase from 24 degrees C to 27 degrees C between 0300 and 0700 h) and constant T(a) (27 degrees C over 24 h). At cyclic T(a), the circadian nadir of T(core) rhythm was significantly advanced, while T(core) was significantly lower from 2300 to 0200 h and significantly higher from 0600 to 1000 h. The nocturnal concentration of 6-hydroxymelatonin sulfate in the urine during sleep was significantly higher during cyclic T(a). Waking sensation just after rising was significantly better with cyclic T(a). (Skin temperatures in the extremities-T(a)) were significantly higher with cyclic T(a) especially during the evening and night. Our results suggest that gradual change of room temperature in the evening and early morning is important in terms of sleep promotion and fresh awakening. It seems probable that mankind has been evolved to have deeper sleep under the influence of cyclic T(a) around dusk and dawn.

Circadian rhythm abnormalities in the acute phase of cerebral infarction correlate with poor prognosis in the chronic phase

The aim of this study was to determine circadian rhythm abnormalities in patients with acute cerebral infarction and their relationship with prognosis in the chronic phase. The subjects were 50 patients who were admitted within 48 h of onset. Rectal temperature and wrist motor activity were recorded during the acute phase. Time-series data were assayed by MEM spectral analysis. Functional prognosis (degree of handicap) was assessed at 3 months after stroke onset by the modified Rankin Scale. Ambulatory patients tended to exhibit circadian rhythm in rectal temperature and/or wrist activity rhythms, whereas non-ambulatory patients did not ( P < 0.001) in the acute phase of ischemic stroke. Our findings suggest the biological rhythms of rectal temperature and wrist activity during the acute stroke phase might be a possible prognostic indicator of their chronic phase.

The influence of time of day and partial sleep loss on muscle strength in eumenorrheic females

Disrupted sleep is the most common form of sleep deprivation in travellers, shift workers, athletes the night before important competitions and among parents of infants. The influence of partial sleep loss on muscle strength might differ according to the time of testing on the following day. This study was therefore designed to assess the interaction between the effects of partial sleep loss and time of day on muscle strength in females. Eight sedentary eumenorrheic females (mean ± SD; age 30 ± 6 years, height 1.62 ± 0.06 m and body mass 67 ± 5.0 kg) took part in the study, in a counterbalanced design. Measurements of muscle strength were carried out at 06:00 and 18:00 hours after the one control night (no sleep loss) and the one night of partial sleep loss, during menses. Muscle strength measures included isokinetic (at 1.05, 3.14 rad s−1; 90° range of motion) and isometric peak torque (at 60° of knee flexion) of knee extensors and flexors (dominant leg). In addition, isometric force of knee extensors with super-imposed electrical twitches (50 Hz, 250 V, 200 μs pulse width) was measured using the same procedure in order to control for motivation. Rectal temperature was measured during the 30 min before muscle strength measurements. Partial sleep loss consisted of allowing 2.5 h sleep (between 03:00 and 05:30 h), whilst in the control condition (no sleep loss) subjects retired between 22:30 and 23:30 h, rising at 05:30 hours. All measurements were conducted at just one phase of the menstrual cycle (menses) to prevent any masking effect due to different phases of the menstrual cycle. In both conditions (with and without partial sleep loss) a diurnal variation was observed in peak torque of knee flexors at 1.05 (F 1,7 = 5.5, p < 0.05) and 3.14 rad s−1 (F 1,7 = 8.0, p < 0.05); values at 18:00 hours were 4.5 and 5.9% higher than at 06:00 hours, respectively. No significant diurnal variation was observed for the other muscle strength measures. No significant effect of partial sleep loss or interaction effect (sleep×time of day) was observed for muscle strength measures. However, the performance rhythms were in phase with the circadian rhythm in rectal temperature. Partial sleep deprivation over one night did not have any adverse effect on maximal muscle strength, nor on diurnal variations of muscle strength indices. As the effect of time of day was observed with some of the muscle strength measures, it is suggested that, in designing future studies using females, the control of time of day is essential.

Circadian rhythm of rectal temperature in humans under different ambient temperature cycles

1. The present study is aimed at knowing whether ambient temperature ( T a) cycles exert any influence on circadian rhythm of rectal temperature ( T re) in humans. 2. Three different T a conditions were provided: (1) T a was kept constant at 25°C for 24 h (Constant). (2) T a decreased from 25°C to 22°C over 4 h from 1800 to 2200 h, was then kept constant at 22°C for additional 6 h and increased to 25°C over 4 h from 0400 to 0800 h (FLR). (3) T a was changed reversibly from 25°C through 28°C to 25°C with identical time schedule like FLR (RHF). 3. Minimum level and evening decreasing rate/morning increasing rate in T re were significantly the lowest and greatest in FLR.

Experimental separation of time of day and homeostatic influences on sleep.

The purpose of the present study was to evaluate the simultaneous effects on sleep of prior time awake (PRW) and time of day (TOD). Eight male subjects spent 13 days in an isolated sleep lab and had three 8-h baseline sleeps and then 18 4-h sleeps, distributed to provide three sleeps starting at 2400, 0400, 0800, 1200, 1600, and 2000. The three sleeps were preceded by 4, 8, and 12 h of PRW, respectively. ANOVA showed that TST and subjective sleepiness increased with PRW and with closeness to the trough of the circadian rhythm of rectal temperature, whereas sleep latency showed the opposite pattern, and rapid eye movement sleep (REM) latency strongly decreased with PRW and with closeness to the trough. Slow-wave sleep (SWS) increased with PRW, whereas SWS latency and final time awake decreased. REM sleep increased with closeness to the circadian trough, and time awake decreased. Multiple-regression analysis showed that REM latency was closely related to increased SWS in the first sleep cycle, reduced SWS latency, and increased PRW [a short PRW before sleep at noon yielded an extremely short (14 min) REM latency]. Sleep latency and final time awake showed almost exactly the same relationship to TOD and PRW. It is concluded that both homeostatic and circadian influences simultaneously affect sleep, that REM latency is very sensitive to the need for SWS, and that the circadian acrophase strongly interferes with sleep. It should be emphasized that the conclusions should not be extrapolated to longer (> 12 h) wake spans.

Circadian rhythm of fever induced by interferon- α in mice

The influence of dosing time on the fever induced by interferon-α (IFN-α) was investigated in ICR male mice under light-dark cycle. There was a significant circadian rhythm in rectal temperature, as an index of fever, at 1 hr after IFN-α (10 MIU kg , i.V.) injection. The rhythmic pattern resembled overall the rhythm occuring in the nondrugged state. IFN-α increased rectal temperature during the light phase, but not during the dark phase. The fever induced by IFN-α was blocked by indomethacin (10 mg kg , i.p.) pretreatment. There was no significant difference of plasma IFN-α concentrations at 0.167, 0.5 and 1 hr after IFN-α injection. Therefore the dosing time dependent difference of fever induced by IFN-α may be caused via that of PGE2 level elevated by IFN-α. The choice of the most appropriate time of day for drug administration may help to achieve rational chronotherapeutics of IFN-α.

Seasonal covariation of the circadian phases of rectal temperature and slow wave sleep onset.

There is a scarcity of well-controlled studies of the seasonal variation in circadian rhythmicity. In the present study, the circadian phase of rectal temperature and the onset of slow wave sleep were studied in a series of twelve 24-h experiments, one each month of the year, for six healthy subjects under controlled conditions in a climatic chamber. In winter, as compared with summer, the average circadian rhythm of rectal temperature was phase delayed by 45 min, and the average onset of slow wave sleep was phase delayed by 40 min. The temporal relationship between the circadian phase of rectal temperature and the timing of slow wave sleep was maintained throughout the year. Habitual rising and retiring times covaried as well. Furthermore, the circadian rhythm of rectal temperature followed the timing of the photoperiod across the year, but had a much smaller range of seasonal variation. Apparently, the seasonal variation in the photoperiodic zeitgeber is largely compensated for by the stabilizing influence of secondary zeitgebers. However, in healthy subjects some effect of photoperiodic variation can still be observed.

The shape of the endogenous circadian rhythm of rectal temperature in humans.

Fourteen healthy subjects have been studied in an isolation unit while living on a 30h "day" (20h awake, 10h asleep) for 14 (solar) days but while aware of real time. Waking activities were sedentary and included reading, watching television, and so forth. Throughout, regular recordings of rectal temperature were made, and in a subgroup of 6 subjects, activity was measured by a wrist accelerometer. Temperature data have been subjected to cosinor analysis after "purification," a method that enables the endogenous (clock-drive) and exogenous (activity-driven) components of the circadian rhythm to be assessed. Moreover, the protocol enables effects due to the circadian rhythm and time-since-waking to be separated. Results showed that the masking effects on body temperature exerted by the exogenous factors appeared to be less than average in the hours before and just after the peak of the endogenous temperature rhythm. This has the effect of producing a temperature plateau rather than a peak during the daytime. The implications of this for mental performance and sleep initiation are discussed.

Effect of different ambient temperature and lipopolysaccharide administration on the circadian rhythm of rectal temperature and hypothalamic PGE 2 production in aged male rats

Old and young male rats (22 and 7 months respectively) were exposed to ambient temperatures of 4 22, 27 and 35°C. The rats' rectal temperatures (RTs) were measured periodically, after exposure to the varying temperatures at different hours during the day. The mean circadian value of RTs in the aged rats was different from that of the young rats. Whereas exposure to low temperatures caused a decrease of 2.0°C in the RTs of the old rats, exposure to heat (35°C) caused an increase of 1°C in their RTs. An injection of 200 μg (intraperitoneally) of E. coli lipopolysaccharide caused them to experience a long period of hypothermia. Elevation in the RTs after the hypothermic period ended was significantly lower in the old rats. However no significant differences in hypothalamic PGE 2 production were to be found between the old and young groups 24 h after pyrogen administration.

Effect of Sex, Menstrual Cycle Phase, and Oral Contraceptive Use on Circadian Temperature Rhythms

The circadian rhythm of rectal temperature was continuously recorded over several consecutive days in young men and women on regular nocturnal sleep schedules. There were 50 men, 21 women with natural menstrual cycles [i.e., not taking oral contraceptives (OCs) (10 in the follicular phase and 11 in the luteal phase)], and 14 women using OCs (6 in the pseudofollicular phase and 8 in the pseudoluteal phase). Circadian phase and amplitude were estimated using a curve-fitting procedure, and temperature levels were determined from the raw data. A two-way analysis of variance (ANOVA) on the data from the four groups of women, with factors menstrual cycle phase (follicular, luteal) and OC use (yes, no), showed that temperature during sleep was lower during the follicular phase than during the luteal phase. Since waking temperatures were similar in the two phases, the circadian amplitude was also larger during the follicular phase. The lower follicular phase sleep temperature also resulted in a lower 24-h tempera...

Circadian rhythm of heat production, heart rate, and skin and core temperature under unmasking conditions in men

Seven healthy men were studied in a 34-h constant routine protocol to investigate whether the daily rhythm of heat production and heat loss has an endogenous circadian component. Under these unmasking conditions (constant bed rest, no sleep allowed, regular food and fluid intake), a significant circadian rhythm could be demonstrated for heat production, heart rate, and skin temperatures but not for the respiratory quotient. Heat production and heart rate were phase locked with a maximum at 1100-1200 h. Proximal skin temperatures (infraclavicular region, thigh, and forehead) followed the same circadian rhythm as rectal temperature, whereas distal skin temperatures (hands and feet) were opposite in phase. These physiological circadian rhythm parameters, as well as biochemical parameters (urinary sodium, potassium, urea, and urine flow), were phase advanced by 25-180 min with respect to the circadian rhythm in rectal temperature. Our findings under unmasking conditions show that the circadian variation in rectal temperature is a consequence of endogenous circadian rhythms in both heat production and heat loss.

Effect of masking on circadian adjustment and interindividual differences on a rapidly rotating shift schedule.

The aim of the present study was to define the effect of masking on the estimation of circadian adjustment of and interindividual differences between nurses on a rapidly rotating shift schedule. The phase shift of the circadian rhythm of rectal temperature was studied in 17 subjects. The following three different methods for estimating the circadian phase shift were compared: (i) cosinor analysis, (ii) a method using normative endogenous data in which the masking effects are removed ("purification"), and (iii) a method using normative endogenous data in which the masking effects are not removed. The mean phase delay during the second night shift (compared with the morning shift) was 6.3 h according to the cosinor analyses of the raw data and 6.2 h according to the cross-correlation method of the raw data. When the masking effects were removed ("purification"), the phase shift was only 1.7 h. Diurnal type did not significantly explain the differences between individuals in the amount of phase shift of the raw data but was the only significant factor, explaining 32% of the variation between individuals in the phase shift of the purified data. Masking effects on body temperature should be taken into account before any definite conclusions can be drawn about the relation between individual factors and the adjustment of the circadian rhythm of body temperature.

Estimating the endogenous component of the circadian rhythm of rectal temperature in humans undergoing normal sleep/activity schedules

Abstract Continuous recordings have been made of rectal temperature for up to 23 consecutive days, using 13 subjects living a normal routine of sleep and activity. A series of purification methods have been developed that enable the direct effects of sleep and activity upon body temperature to be taken into account; this allows a daily estimate of the “unmasked”; circadian rhythm to be made. Results indicate that the purified, unmasked rhythm showed more daily phase variation than the raw (masked) data. These findings are discussed with regard to the stabilizing effect upon the measured circadian rhythm that masking factors have, and in terms of estimating the phase variability of the endogenous component of the circadian rhythm.

Inducing jet lag in older people: Adjusting to a 6-hour phase advance in routine

A 15-day simulated jet lag experiment was performed in a time isolation laboratory using 15 old women (79–91 years, mean 82.9 years) and 10 old men (71–86 years, mean 80.5 years). After five full days and nights on the subject's habitual routine, the waketime of night 6 was advanced by 6 h, truncating the sleep episode. All subsequent events occurred 6 h earlier than normal. Adjustment to the phase shift was evaluated by the circadian rhythm in rectal temperature (measured every minute), polysomnography of each sleep episode, and daily averages of mood, activation, and performance speed. While the circadian rhythm amplitude reduction consequent upon the phase shift showed a tendency to be longer lived in the old men, both old groups showed fairly rapid adjustment of the timing of their circadian temperature rhythm, comparable (if not better) to that observed earlier in a study of middle aged men. However, sleep disruption (and daytime sleepiness) appeared to be longer lived in the elderly, showing little of the recovery over time observed in younger subjects. Thus, there appeared to be some separation in the elderly of the sheep disruption and circadian rhythm disruption effects of jet lag.

坐剤の融解時間に及ぼす直腸温日内リズムの影響

坐剤の融解時間に及ぼす直腸温日内リズムの影響

Circadian rhythm of rectal temperature in man with two different types of clothing

We compared the circadian rhythm of human rectal temperature with two different types of clothing at an ambient temperature of 27.5 degrees +/- 0.5 degrees C and a relative humidity of 40 +/- 10%. One clothing covered the whole body area except for the head, hands and feet (Type A, weight 475 g, 0.98 clo), the other covered the trunk, upper arms and thighs (Type B, weight 366 g, 0.93 clo). Major findings are summarized as follows: (1) Late evening fall after retiring and a morning rise after rising in the rectal temperature rhythm were significantly quicker in Type B than in Type A. (2) Late evening rise after retiring and a morning fall after rising in the skin temperatures of the extremities were quicker in Type B than in Type A. (3) A range of oscillation in the circadian rectal temperature rhythm was significantly larger in Type B than in Type A. It was suggested that the quicker late evening rise and morning fall of the skin temperatures in the extremities after retiring and rising, respectively, might be responsible for the quicker late evening fall and morning rise of the circadian rectal temperature.

体温概日リズムを検索し得た脳腫よう続発性低体温症の１例

An elderly case of secondary hypothermia associated with brain tumor was reported. An 84-year old woman developed hypothermia. Although her rectal temperature remained below 37 degrees C, the circadian rhythm of rectal temperature was preserved. Brain computerized tomography (CT) and brain magnetic resonance imaging (MRI) revealed a solitary brain tumor involving the hypothalamus. It appears that her hypothermia may not be due to inability to thermoregulate but to stem from her abnormal target temperatures. Body temperature is normally controlled at around 37 degrees C, but in this patient thermoregulation might have been reset at a lower temperature.

4859826 Simultaneously cutting and welding sheet metal using laser energy : Albert J Hess assigned to Laser Applications Inc

1.1.|The circadian rhythm of rectal temperature and the sleep-wake cycle can persist independently of each other and of zeitgebers, and seem to be controlled by separate oscillators.2.2.|‘Masking’ of temperature by sleep or zeitgeber signals is to be distinguished from entrainment mechanisms.3.3.|Heat production and conductance coact in generating the temperature rhythm.4.4.|Circadian variations in system properties, as observed, e.g. in threshold, need to be confirmed in the absence of a sleep-wake (light-dark) cycle.