Amplitude Of Temperature Rhythm Research Articles

Menstrual Cycle Effects on Sleep.

Subjective and objective sleep changes occur during the menstrual cycle. Poorer sleep quality in the premenstrual phase and menstruation is common in women with premenstrual symptoms or painful menstrual cramps. There is increased sleep spindle activity from follicular to luteal phase, potentially progesterone related. Luteal phase changes also include blunted temperature rhythm amplitude and reduced rapid eye movement sleep. Women with polycystic ovary syndrome should be screened for sleep disordered breathing. Short sleep duration is associated with irregular menstrual cycles, which may impact reproductive health. Menstrual cycle phase and menstrual-related disorders should be considered when assessing women's sleep complaints.

Age-related changes in core body temperature and activity in triple-transgenic Alzheimer’s disease (3xTgAD) mice

SUMMARYAlzheimer’s disease (AD) is characterised, not only by cognitive deficits and neuropathological changes, but also by several non-cognitive behavioural symptoms that can lead to a poorer quality of life. Circadian disturbances in core body temperature and physical activity are reported in AD patients, although the cause and consequences of these changes are unknown. We therefore characterised circadian patterns of body temperature and activity in male triple transgenic AD mice (3xTgAD) and non-transgenic (Non-Tg) control mice by remote radiotelemetry. At 4 months of age, daily temperature rhythms were phase advanced and by 6 months of age an increase in mean core body temperature and amplitude of temperature rhythms were observed in 3xTgAD mice. No differences in daily activity rhythms were seen in 4- to 9-month-old 3xTgAD mice, but by 10 months of age an increase in mean daily activity and the amplitude of activity profiles for 3xTgAD mice were detected. At all ages (4–10 months), 3xTgAD mice exhibited greater food intake compared with Non-Tg mice. The changes in temperature did not appear to be solely due to increased food intake and were not cyclooxygenase dependent because the temperature rise was not abolished by chronic ibuprofen treatment. No β-amyloid (Aβ) plaques or neurofibrillary tangles were noted in the hypothalamus of 3xTgAD mice, a key area involved in temperature regulation, although these pathological features were observed in the hippocampus and amygdala of 3xTgAD mice from 10 months of age. These data demonstrate age-dependent changes in core body temperature and activity in 3xTgAD mice that are present before significant AD-related neuropathology and are analogous to those observed in AD patients. The 3xTgAD mouse might therefore be an appropriate model for studying the underlying mechanisms involved in non-cognitive behavioural changes in AD.

Development of fetal and neonatal sleep and circadian rhythms

The origin of sleep and circadian rhythms development is found during the fetal period. Both quiet (NREM) and active (REM) sleep are distinguishable during the last 10 weeks of gestation. Comparable to fetuses, low risk preterm infants recorded at 30-40 weeks postconceptional age, had a similar development of sleep i.e. an increase in quiet sleep and a decrease in indeterminate sleep. A further development in sleep organization characterized by increased slow wave and spindle activity during quiet sleep and coupling with circadian rhythm takes place during the first 6 months of life in both term and preterm infants.Circadian rhythm of fetal heart rate synchronized with maternal rest-activity, heart rate, cortisol, melatonin, and body temperature rhythms is present during the last 10 weeks of gestation. Although maternally influenced, circadian rhythm antenatally becomes ultradian at birth. Both preterm and term infants show a significant increase in circadian body temperature rhythm amplitude during the first 3 months of life.

Phase advance of sleep and temperature circadian rhythms in the middle years of life in humans

Age-related changes in sleep may be linked to modifications in the circadian timing system. This study compared sleep patterns and unmasked circadian temperature parameters between a group of young subjects and a group of middle-aged subjects. Habitual bedtime and waketime were earlier in the middle-aged than in the young. In addition, middle-aged subjects reported a greater orientation toward morningness and they showed an earlier phase of temperature rhythm. No differences were found in amplitude of temperature rhythm or in habitual phase angle between sleep and the temperature rhythm. In conclusion, a phase advance of sleep and temperature circadian rhythm is already apparent in people in their forties and fifties. These changes precede modifications in amplitude or in habitual phase angle.

The paraventricular nucleus of the thalamus alters rhythms in core temperature and energy balance in a state-dependent manner

Exposure to chronic stress facilitates activity within the hypothalamic–pituitary–adrenal (HPA) axis and is associated with enhanced neuronal activity in a discreet set of brain regions, including the posterior division of the paraventricular nucleus of the thalamus (pPVTh). Because HPA function is intimately associated with systems that regulate metabolism, including core temperature and energy balance, we examined the effects of chronic stress on circadian rhythms in temperature, locomotor activity, body weight gain and food intake and adipose depot weights in rats. We also examined the potential role of the pPVTh in mediating these functions using ibotenate lesions of this nucleus. Chronic stress lowered the amplitude of core temperature rhythms, and lesions of the pPVTh blocked this effect in chronically stressed animals, but did not affect the amplitude of temperature rhythms in unstressed controls. In addition, lesions of the pPVTh increased cumulative food intake and overall body weight gain in controls but they increased subcutaneous white adipose depot weight in chronically stressed animals. Thus, the functional paraventricular nucleus of the thalamus appears to inhibit both temperature rhythms and specific white adipose depots only in chronically stressed animals. Together with our previous results, we show that the PVTh affects rhythms in food intake and body weight and is a nexus that differentially regulates core temperature rhythms/HPA activity/specific white adipose depots depending on the stress state of the animal.

Electroconvulsive therapy increases circadian amplitude and lowers core body temperature in depressed subjects

Reduced amplitude of the circadian temperature rhythm and elevated nocturnal body temperature normalize after successful pharmacotherapy of major depression. Core body temperature was continually monitored in three groups: a) 6 depressed patients before an electroconvulsive therapy (ECT) course and b) after an ECT course; and c) 6 healthy, sex-matched controls of similar age. The 24-hour profile of temperature was significantly different in patients pre-ECT than in patients post-ECT or in controls. Post-ECT subjects and controls manifested 24-hour profiles similar to one another. Circadian temperature rhythm amplitude increased after ECT. The mean asleep and mean 24-hour temperatures were significantly higher in patients pre-ECT than post-ECT and controls. We find that ECT restores a disrupted circadian temperature rhythm in depressed patients.

Regulation of the 24-hour rhythm of body temperature in menstrual cycles with spontaneous and gonadotropin-induced ovulation

Objective: To investigate the relation between gonadal steroids and the 24-hour body temperature rhythm. Patient(s): Nineteen normally cycling women. Design: Controlled clinical study in volunteer women. Setting: Clinical hospital. Intervention(s): Eleven women were studied in the early follicular and luteal menstrual phases of cycles with spontaneous ovulation, and 8 women were studied in the early follicular, preovulatory, and luteal phases of cycles with multiple follicular development. Main Outcome Measure(s): Starting at 5:00 P.M., intravaginal body temperature was monitored continuously for 24 hours and its values were related to E 2 and P levels. Result(s): Twenty-four-hour body temperature rhythm parameters were related to the P:E 2 ratio. Very low P:E 2 ratios in the preovulatory phase were associated with a reduced 24-hour mean and an elevated body temperature rhythm amplitude. The progressive increase in the P:E 2 ratio in the early follicular and luteal phases was associated with an increase in the 24-hour mean body temperature and a decrease in the rhythm amplitude. Body temperature differences between the luteal and early follicular phases were less pronounced in cycles with multiple follicular development. Conclusion(s): A woman's body temperature is related to her P:E 2 ratio. Even in the presence of elevated P values, alterations of this ratio may influence negatively the postovulatory rise in body temperature.

The effects of ambient temperature on the body temperature rhythm of rats, hamsters, gerbils, and tree shrews

The daily rhythm of body temperature of male rats, Syrian hamsters, fat-tailed gerbils, and tree shrews was studied by telemetry. All animals were maintained for five days at each of four ambient temperatures (14, 20, 28, and 32°C). The amplitude of the body temperature rhythm of tree shrews was found to decrease as ambient temperature increased. The amplitude of the temperature rhythm of rats was found to remain constant at 14, 20, and 26°C but to be slightly reduced at 32°C. No significant effect of ambient temperature was found on the amplitude of the body temperature rhythm of Syrian hamsters and fat-tailed gerbils. Reductions in rhythm amplitude were due mostly to the curtailment of the daily fall in body temperature with no alteration in the daily peak.

Amplitude reduction of the circadian temperature and sleep rhythms in the elderly.

This study examined the relationship between circadian temperature rhythm amplitude reduction and sleep consolidation parameters in a group of healthy elders experiencing a 6-h phase advance in routine. Twenty-five healthy old people (15 women, 10 men, 77-91 years old) lived in a time-isolation apartment. Throughout the study, subjects were instructed when to go to bed, get up, and take meals. The experiment started with 5 baseline days during which subjects were kept to a daily routine corresponding to their habitual sleep-wake cycle. The wake time of the 6th night was phase-advanced by 6 h and the routine for the remainder of the experiment was held constant at the new earlier phase position. Rectal temperature was recorded continuously and all sleep episodes recorded polygraphically. Time series of temperature data for each subject were analyzed by complex demodulation (CD). Five of the subjects were excluded from analysis because the percentage of variance accounted for by the remodulate was less than 55% for the postshift days and one subject was excluded because he showed an average sleep efficiency of less than 55% during baseline. In the remaining 19 subjects, the phase shift produced a large decrease of the mean amplitude of the temperature circadian rhythm (from 0.45 degree C to 0.25 degree C). During the first 3 nights following the phase shift, sleep efficiency was decreased and amount of wakefulness in the first half of the night (WFirst) was increased. No effect was found for the amount of wake in the second half of the night (WSecond). The change in amplitude of the temperature rhythm was significantly correlated with change in sleep efficiency (r = 0.5; p = 0.03) and with change in WFirst (r = -0.7; p < 0.001). There was no correlation between change in the amplitude of the temperature rhythm and WSecond. These results suggest that in older subjects, amplitude of the output of the circadian oscillator might indeed be involved in the sleep consolidation process but, in the first, rather than the second half of the night.

Age-related changes in both circadian and seasonal rhythms of rectal temperature with special reference to senile dementia of Alzheimer type.

The biological rhythms of rectal temperature were documented in young (circadian variations) and elderly (circadian and seasonal variations) human subjects either in apparent good health or suffering from senile dementia of Alzheimer type (SDAT). All the subjects were synchronized. Data obtained showed a decrease of the body core temperature rhythm amplitude in the healthy elderly for each documented season but not in patients with SDAT. Seasonal variations in these rhythms were observed in these elderly groups of persons.

Suprachiasmatic dinuclear lesion alters circadian temperature rhythm's amplitude and timing in light-dark synchronized rats

Suprachiasmatic dinuclear lesion alters circadian temperature rhythm's amplitude and timing in light-dark synchronized rats