Deep Body Temperature Rhythms Research Articles

Prenatal exposure to alcohol alters the light response in postnatal circadian rhythm

We studied the effect of prenatal exposure to alcohol on later circadian rhythm in the rat. In the normal light–dark cycle, an 8-h phase advance brought forward the deep body temperature rhythm in control rats, although it had a smaller effect in prenatally ethanol-exposed rats. In long constant darkness, the phase response of the deep body temperature rhythm to a light pulse at the early subjective night was less marked in ethanol-exposed rats in comparison to controls. These results indicate that prenatal exposure to alcohol has a long-lasting effect on the light responsiveness of the deep body temperature circadian rhythm.

The Sleep-Evoked Decrease of Body Temperature

The circadian rhythm of deep body temperature consists of both an endogenous component and evoked components resulting from exogenous influences. Previous studies of the sleep-evoked effect have failed to control confounding influences, so that the effect of sleep per se has not been established. In the present study, eight good sleepers had their rectal temperatures recorded for 24 hours in each of two laboratory conditions employing a constant routine to control exogenous influences. Sleep was allowed at night in one condition. Following sleep onset, body temperature dropped more rapidly and remained lower than when wakefulness continued over the same time, resulting in a mean sleep-evoked decrease of 0.31 +/- 0.09 degree C. Fourier regression analysis showed a significant 24-hour (circadian) temperature rhythm, together with a 12-hour harmonic rhythm, in each condition. Circadian rhythm parameters were also altered by the sleep-evoked (or masking) effect, with the amplitude increased and the mean decreased when subjects slept at night in the constant routine. It was suggested that a constant routine methodology be used in studies of circadian rhythm differences and that Fourier regression be used in preference to simple cosine curve fitting to give a better approximation of the temperature rhythm.

Rectal temperature of normal babies the night after first diphtheria, pertussis, and tetanus immunisation.

Continuous rectal temperature recordings were made from 32 babies the night after their first diphtheria, pertussis, and tetanus immunisation and compared with recordings made before immunisation. Tog values of clothes and wrapping and room temperatures were also recorded. We found that immunisation the day before disturbs the normal night time rhythm of deep body temperature. The rectal temperature of immunised babies was significantly higher than non-immunised babies from two hours into the night. We also found that there were considerable individual variations in the extent of disturbance of temperature rhythm. They were not correlated with thermal environment. There is no reason to suppose that these mild physiological responses to immunisation are in any way harmful.

A model of the circadian rhythm of deep body temperature

A simple model for the human circadian rhythm of deep body temperature is described. The model accounts for both the endogenous circadian rhythm, and the principal masking effects resulting from sleep, activity, and ambient temperature. The Continuous System Modelling Program (CSMP) language was then used to simulate deep body temperature, as described by the model.

Postoperative deep body temperature rhythm.

The postoperative deep body temperature rhythms of fifteen patients who received aorto-coronary bypass surgery (group I), and of seven patients who received non-cardiac major surgery (group II), were studied. Postoperative patients, especially those who received aortocoronary bypass surgery, showed greatly disturbed deep body temperature rhythm. There existed infradian and ultradian rhythm in both groups, and there existed two patients in group I who did not show sinusoidal rhythm. The patients of group I also showed a longer period of rhythm than did those of group II. The mesor and amplitude of the patients in group I showed a greater individual variation than did those in group II. The acrophase of both groups deviated widely. The patients who underwent cardiac surgery needed a longer time for temperature rhythm recovery than did those who underwent general surgery.

On reproducibility of circadian rhythms in man (author's transl)

On the basis of our own experimental data and those from the literature, the reproducibility of day-night variations in physiological functions--their 'circadian pattern'--is examined in five sections. They concern the problem of intra- and interindividual variability, demonstrated by the rhythm of deep body temperature, the dependence of the pattern on experimental conditions, and as further examples circadian rhythms in the endocrine system, in blood constituents, in blood pressure and in psychomotor performance. The survey is considered to contribute to the question of how important the circadian temporal structure may be in the search for reference values and hence in diagnosis.

Two mechanisms of rephasal of circadian rhythms in response to a 180° phase shift (simulated 12‐hr time zone change)

A model developed by Wever (1966) is considered. The model describes the behavior of circadian rhythms in response to photoperiod phase shifts simulating time zone changes, as a function of endogenous periodicity, light intensity, and direction of phase shift. A description is given of an investigation conducted to test the model upon the deep body temperature rhythm in unrestrained subhuman primates. An evaluation is conducted regarding the applicability of the model in predicting the type and duration of desynchronization induced by simulated time zone changes as a function of endogenous periodicity.

Chronotypic action of theophylline and of pentobarbital as circadian zeitgebers in the rat.

In the rat the deep body temperature rhythm, monitored by telemetry, can be reset in a predictable direction by a stimulant (theopylline) and by a depressant (pentobarbital). When the drugs are applied immediately before or during the early active phases of the circadian cycle, the rhythm is set back (phase delay). When applied later, past the thermal peak, theophylline, but not pentobarbital, shifts the rhythm ahead (phase advance). Theophylline and pentobarbital in addition to having a number of already established pharmacological properties are now further identified as chronobiotics: they are drugs that may be used to alter the biological time structure by rephasing a circadian rhythm.

Noradrenergic control of circadian rhythms in Cebus albifrons.

AbstractManifestation of biologic oscillations (e.g., body temperature 24‐hour wave form) is the summation of the exogenous and endogenous response mechanisms of the biologic clock. Biologic rhythm asynchrony results from a rapid change in the environment presented to the time sensors. The destruction of noradrenergic terminals in a male Cebus albifrons by 6‐hydroxydopa interrupted the transmission of information from the defined environment to the biologic clock as evidenced by removal of the exogenous components of the 24‐hour deep body‐temperature (DBT) wave form; i.e., decrease in DBT rhythm was no longer associated to lights off, and the level about which this rhythm fluctuated was reduced. In contrast the daily heart rate rhythm was less affected.