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

Axillary and Thoracic Skin Temperatures Poorly Comparable to Core Body Temperature Circadian Rhythm: Results from 2 Adult Populations

Data from 2 separate studies were used to examine the relationships of axillary or thoracic skin temperature to rectal temperature and to determine the phase relationships of the circadian rhythms of these temperatures. In study 1, axillary skin and rectal temperatures were recorded in 19 healthy women, 21 to 36 years of age. In study 2, thoracic skin and rectal temperatures were recorded in 74 healthy women, 39 to 59 years of age. In both studies, temperatures were recorded continuously for 24 h while subjects carried out normal activities. Axillary and thoracic probes were insulated purposely to prevent ambient effects. Cosinor analysis was employed to estimate circadian rhythm mesor, amplitude, and acrophase. In addition, correlations between temperatures at various measurement sites were calculated and agreement determined. The circadian timing of axillary and skin temperatures did not closely approximate that of rectal temperature: the mean acrophase (clock time) for study 1 was 18:57 h for axillary temperature and 16:12 h for rectal; for study 2, it was 03:05 h for thoracic and 15:05 h for rectal. Across individual subjects, the correlations of axillary or thoracic temperatures with rectal temperatures were variable. Results do not support the use of either axillary or skin temperature as a substitute for rectal temperature in circadian rhythm research related to adult women.

Effects of different light intensities during the daytime on circadian rhythm of core temperature in humans

The present study was to determine the effects of bright light exposure during the daytime on core temperature rhythm. Eight female students participated as subjects. They were exposed to bright light of 5000 lux or dim light of 200 lux for 13 hours (06:30-19:30) for two consecutive days. Except the sleep period (22:30-06:30) and during the bright light exposure, light intensity was controlled at 200 lux. Rectal temperature data were collected every 10 min throughout the whole experimental period. The mean level of rectal temperature was not significantly different between the bright and the dim light conditions. However, the evening fall and the morning rise of rectal temperature were significantly greater in the bright light conditions on Day 2 compared to the dim. Furthermore, cosinor analysis showed that the acrophase of rectal temperature rhythm was earlier on Day 2 in the bright light conditions than the dim, and was significantly delayed on Day 2 compared to Day 1 in the dim light conditions. These results suggest that low intensity during the daytime for two consecutive days may induce a phase delay of core temperature rhythm rather than the bright light exposure at least in normally entrained female subjects.

Effects of different types of clothing on circadian rhythms of core temperature and urinary catecholamines

This study investigated the effects of three different types of clothing on the circadian rhythms of core temperature and urinary catecholamines. One type of clothing consisted of long-sleeved shirts, full-length trousers, and socks (Type L, 1,042 g); the second type was of half-sleeved shirts and knee-length trousers (Type H, 747 g); the third type was of Type H during the daytime and Type L during night sleep (Type M). Six healthy females participated in this study where rectal temperature, skin temperatures, heart rate, and urinary catecholamines were continuously measured for 37.5 h at an ambient temperature of 23.8 +/- 0.2 degrees C and a relative humidity of 60 +/- 5%. The results were as follows: (1) The nocturnal minimum of rectal temperature decreased significantly in the sequence Type L < Type M < Type H clothing, and 27.2 and 12.4% of the circadian amplitude were influenced by type of clothing during the daytime and the nighttime, respectively. (2) The rise of skin temperatures in the extremities increased significantly more after the subjects retired for sleep with Type M or Type H clothing than with Type L. (3) Urinary catecholamines decreased more in the evening and increased more in the morning with Type H and Type M clothing than with Type L. These results show that the circadian rhythm of core temperature, especially the nocturnal minimum value, was influenced by the type of clothing worn not only during the nighttime, but also during the daytime.

Effects of two types of clothing on the day-night variation of core temperature and salivary immunoglobulin A

Circadian variations in core temperature, skin temperatures, heart rate, and salivary immunoglobulin A (IgA) were compared in subjects wearing two different types of clothing that covered, or left uncovered, their extremities. The experiments were carried out on six female subjects at an ambient temperature of 24 +/- 0.5 degrees C and relative humidity of 50 +/- 5%. One type of clothing consisted of long-sleeved shirts, full-length trousers, and socks (Type L: 1042 g, 1.048 clo); the other was half-sleeved shirts and knee-length trousers (Type H: 747 g, 0.744 clo). The main results were as follows: (i) The level of rectal temperature during night sleep was significantly lower with Type H than Type L clothing, and cosinor analysis indicated a significantly higher circadian amplitude with Type H clothing. (ii) Skin temperatures in the lower extremities increased significantly more on retiring to sleep with Type H than Type L clothing. (iii) Heart rate was significantly lower with Type H than Type L clothing during the sleep period. (iv) The day-night variation of salivary IgA showed a pattern that was the inverse of that of rectal temperature (i.e., low in the daytime and high in the nighttime), and the concentration of salivary IgA was significantly higher with Type H than Type L clothing at 02:30. (v) Subjectively, the self-assessed sleep quality was better with Type H clothing. These results suggest that clothing that leaves the extremities uncovered might be regarded as favorable at the moderate temperature since it induces good sleep and activates the immune response.

Acclimatization effect on the evening fall in core temperature under the influence of two types of clothing

This paper reports the effect of acclimatization on the evening fall in core temperature under the influence of two different types of clothing. Two groups of subjects dressed in either knee-length skirts or full trousers during the daytime for the three months from April to June. To compare the circadian rhythm of core temperature, the experiments were carried out before and after the three month program of acclimatization. It was found that the subjects who had worn knee-length skirts showed lower rectal temperatures during the nighttime and a bigger amplitude of circadian rhythm in July than in March.

The effect of ambient temperature extremes on tympanic and oral temperatures

Exposure to ambient temperature extremes immediately preceding emergency department triage may affect tympanic membrane temperatures taken with infrared emission detection thermometers. In a prospective, unblinded study, 20 healthy subjects, on 2 separate days, underwent 15-minute exposures to hot (43.5 degrees C) and cold (-5 degrees C) temperature extremes in an environmental control room (ECR). Tympanic and oral temperatures were taken at baseline and at 2-minute intervals for 20 minutes after exiting the ECR. Rectal temperatures remained stable during the exposures. Oral temperatures rose significantly after hot exposure (P less than .05; max 0.4 degrees C) and briefly decreased after cold exposure (max 0.5 degrees C). Tympanic temperatures were elevated for 20 minutes after hot exposure (max 0.8 degrees C) and decreased briefly only in male subjects after cold exposure (max 0.7 degrees C). Individuals demonstrated wide variability in their temperature responses. Tympanic and oral temperatures taken within the first 20 minutes after exposure to outdoor temperature extremes may fail to accurately reflect the patient's true temperature.