Thermoregulatory Responses to Desert Heat: Age, Race and Sex

Yousef, Mohamed; Dill, D. B.; Vitez, Terry S.; Hillyard, Stanley D.; Goldman, A.

doi:10.1093/geronj/39.4.406

Cited by 55 publications

(22 citation statements)

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“…In subjects who are awake, older men exhibit lower heat tolerance than younger men. The ability to maintain core body temperature (Sagawa et al 1988;Inoue et al 1991;Inoue 1996) and the sweating response (Inoue et al 1991;Hellon and Lind 1958) during heat exposure appear to be reduced, although some results throw doubt on this conclusion (Yousef et al 1984). These effects on core body temperature and sweat rate are secondary effects attributable to decreased physical fitness, as they have not been observed in physically fit older men.…”

Section: Introductionmentioning

confidence: 99%

Effects of mild heat exposure on sleep stages and body temperature in older men

2004

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The purpose of this study was to examine the effects of mild heat exposure on sleep stages and body temperature in older men. Ten healthy male volunteers with a mean age of 69.2 +/- 1.35 years served as subjects. The experiments were carried out under two different sets of conditions: 26 degrees C 50% relative humidity (RH) and 32 degrees C 50% RH. The subjects slept from 2200 hours to 0600 hours with a cotton blanket and wearing short-sleeve pajamas and shorts on a bed covered by a sheet. Electroencephalogram, electro-occulogram and mental electromyogram recordings were made through the night. Rectal and skin temperatures were measured continuously. No significant differences were observed in sleep onset latency. In time spent in each sleep stage, wakefulness was significantly increased at 32 degrees C than at 26 degrees C. The total amount of wakefulness increased and rapid eye movement sleep (REM) decreased at 32 degrees C compared to 26 degrees C. The fall in rectal temperature was significantly suppressed and the mean skin temperature was significantly higher at 32 degrees C than at 26 degrees C. These results suggest that, for older men, even mild heat exposure during the nighttime sleep period may increase thermal load, suppress the decrease of rectal temperature, decrease REM, and increase wakefulness and whole-body sweat loss.

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Section: Introductionmentioning

confidence: 99%

Effects of mild heat exposure on sleep stages and body temperature in older men

2004

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“…Further, lower circadian amplitudes and advance phases (Czeisler et al 1992) lead to reduced sleep promotion by the circadian pacemaker and reduced homeostatic pressure for sleep (Buysse et al 1993;Dijk et al 2000). Meanwhile, the ability of older subjects to maintain their core body temperature during heat and cold exposure also appears to be reduced in wakeful subjects (Sagawa et al 1988;Inoue et al 1992;Inoue 1996), although there have been conflicting results (Yousef et al 1984). The subjective sensation of heat and cold also reduce sensitivity (Taylor et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Effects of season on sleep and skin temperature in the elderly

Okamoto-Mizuno

Tsuzuki

2009

Int J Biometeorol

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The effects of season on sleep and skin temperature (Tsk) in 19 healthy, elderly volunteers were investigated. Measurements were obtained in summer, winter, and fall, and activity levels were monitored using a wrist actigraph system for five consecutive days. The temperature and humidity of the bedrooms of the subjects' homes were measured continuously for five days. During actigraphic measurement, Tsk during sleep was measured for two nights. The bedroom temperature and humidity significantly increased in summer compared to winter and fall. In summer, the total sleep time decreased (mean +/- SE min; summer, 350.8 +/- 15.7; winter, 426.5 +/- 14.2; fall, 403.2 +/- 16.4) and wakefulness increased (P < 0.003) compared to those in fall or winter. The sleep efficiency index that was derived from wrist actigraphy was significantly decreased (P < 0.001) in summer (81.4 +/- 2.9%) compared with winter (91.6 +/- 1.3%) or fall (90.2 +/- 1.2%). The forehead Tsk significantly increased, while the chest and thigh Tsks were decreased in summer compared to those in fall or winter. These results suggest that, in the elderly, sleep is disturbed in summer more than in other seasons, and that this disturbance is related to fluctuations in Tsk.

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“…All the above studies have been conducted in men and boys, and it is not known whether these findings are applicable to women and girls, in whom the physiological responses to heat stress are different than those of males (Bar-Or 1996Yousef et al 1984). Women and girls, for example, generally sweat less than men and boys when exposed to identical environmental and exercise conditions (Bar-Or 1996;Kawahata 1960).…”

Section: Introductionmentioning

confidence: 99%

Voluntary drinking and hydration in non-acclimatized girls exercising in the heat

Wilk

Rivera-Brown²,

Bar‐Or

2007

Eur J Appl Physiol

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The intent of this study was to assess the influence of drink flavor and composition on voluntary drinking and hydration status in girls exercising intermittently in the heat (35 +/- 1 degrees C, 45-50% relative humidity). Twelve physically active, nonacclimatized girls (9-12 years) performed three 3 h identical sessions, each consisting of four 20 min cycling bouts at 50% (VO(2max)), separated by 25 min of rest. One of the three beverages (chilled to 8-10 degrees C) was assigned to each session: unflavored water (W), grape-flavored water (FW) and grape-flavored water plus 6% carbohydrate and 18 mmol l(-1) NaCl (CNa). Drinking was ad libitum. Body weight (BW), drink intake (DI), heart rate, rectal and skin temperatures, and perceptions of thirst and stomach fullness were monitored periodically. Total DI was 759, 940, 1,045 g in W, FW and CNa, respectively (P < 0.05 for CNa-W and FW-W). BW changes were -0.15, 0.16, and 0.45% in W, FW and CNa, respectively, but only the difference between CNa and W was significant (P < 0.05). Other physiological and perceptual variables were not different between trials. In conclusion, beverage flavoring regardless if its combination with carbohydrate and NaCl, mildly enhanced voluntary drinking in young non-acclimatized girls. In contrast to previous research in young boys, euhydration was maintained in the girls by an adequate intake of unflavored water.

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Thermoregulatory Responses to Desert Heat: Age, Race and Sex

Cited by 55 publications

References 0 publications

Effects of mild heat exposure on sleep stages and body temperature in older men

Effects of mild heat exposure on sleep stages and body temperature in older men

Effects of season on sleep and skin temperature in the elderly

Voluntary drinking and hydration in non-acclimatized girls exercising in the heat

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