Effects of humid heat exposure in later sleep segments on sleep stages and body temperature in humans

Abstract

This study sought to investigate the effects of humid heat exposure in later sleep segments on sleep stages and body temperature in humans. The subjects were eight healthy males, from whom informed consent had been obtained. The experiments were carried out under three different sets of conditions: a control climate [air temperature (Ta)=26 degrees C, relative humidity (RH)=50%] (C); a humid heat climate (Ta=32 degrees C, RH=80%) (H); and a humid heat exposure in later sleep segments (C for the first 3 h 45 min, followed by a 30-min transition to H, which was then maintained for the last 3 h 45 min) (C-H). Electroencephalogram, EOG, and mental electromyogram, rectal temperature (Tre), and skin temperature (Tsk) were continuously measured. The total amount of wakefulness was significantly increased in H compared to C-H or C. Compared to C, wakefulness in C-H and H was significantly increased during later sleep segments. Tre and mean Tsk were significantly higher in H than in C-H or C. In C-H, Tsk and Tre increased to levels equal to those observed in H after Ta and RH increase. Whole body sweat loss was significantly lower in C-H and C than in H. These results suggest that humid heat exposure in the later sleep segment reduces thermal load as compared to full-night humid heat exposure. In daily life, the use of air conditioning in the initial sleep hours can protect sleep and thermoregulation.

The Effects of Low Air Temperatures on Thermoregulation and Sleep of Young Men While Sleeping Using Bedding

“…Generally, for a waking person, Ts quickly reduces in proportion to the decrease in Ta in a cold environment, and afterwards, Tre also decreases. For sleeping persons, when the Ts were kept at a higher level in the hot environment, the Tre did not decrease so much and were kept at a higher level [26]; or Ts changed following the Ta, and the Tre varied in accordance with the Ts [27]. However, it is intriguing in the present study that when the Ts was kept at a higher level by using the bedding, except for the head, the internal body was cooled by head-cooling.…”

Clima, sociedad, riesgos y ordenación del territorio

“…El calor puede llevar, entre otros efectos, a alteraciones y privaciones de éste debidos a la puesta en marcha de los procesos de termorregulación (Buguet, 2007). Concretamente, las temperaturas superiores a las del confort pueden influir en el aumento del desvelo y en la disminución de las fases REM (Rapid Eye Movement) y SWS (Slow-wave Sleep) (Haskella et al, 1981;Okamoto y Mizuno 2005. Las alteraciones del sueño se dan con mayor incidencia, al igual que el riesgo general de morbi-mortalidad durante los episodios de calor, en personas con avanzada edad (Buguet, 2007;Koppe et al, 2004).…”

Análisis espacio-temporal de las noches cálidas en el litoral mediterráneo de España

“…El calor puede llevar, entre otros efectos, a alteraciones y privaciones de éste debidos a la puesta en marcha de los procesos de termorregulación (Buguet, 2007). Concretamente, las temperaturas superiores a las del confort pueden influir en el aumento del desvelo y en la disminución de las fases REM (Rapid Eye Movement) y SWS (Slow-wave Sleep) (Haskella et al, 1981;Okamoto y Mizuno 2005, 2012. Las alteraciones del sueño se dan con mayor incidencia, al igual que el riesgo general de morbi-mortalidad durante los episodios de calor, en personas con avanzada edad (Buguet, 2007;Koppe et al, 2004).…”