Influence on human sleep patterns of lowering and delaying the minimum core body temperature by slow changes in the thermal environment

Exercise Sciences Research Group, Tokyo Metropolitan Institute of Gerontology, Itabashi, Tokyo, Japan.
Sleep (Impact Factor: 4.59). 07/2007; 30(6):797-802.
Source: PubMed


We hypothesized that appropriate changes in thermal environment would enhance the quality of sleep.
Controlled laboratory study.
Healthy young men (n = 7, mean age 26 years).
Nocturnal sleep structures in semi-nude subjects were compared between a condition where an ambient temperature (Ta) of 29.5 degree C was maintained throughout the night (constant Ta), and a second condition (dynamic Ta) where Ta changed slowly within the thermoneutral range (from 27.5 C to 29.5 degree C).
Statistically significant (P < 0.05) results included a lower and a later occurrence of minimum core body temperature (Tc), and a longer duration of slow-wave (stages 3+4) sleep in dynamic versus constant T. However, total sleep time, sleep efficiency, the total durations of light (stages 1+2) and rapid eye movement sleep, and the latencies to sleep onset, slow-wave sleep, and rapid eye movement sleep did not differ between conditions.
Lowering the minimum and delaying the nadir of nocturnal Tc increases slow-wave sleep (probably by an increase of dry heat loss); use of this tactic might improve the overall quality of sleep.

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    • "They demonstrated a SkBF circadian variation that was out of phase with the T re circadian variation by 4 h; decreases in T re were preceded by increases in extremity SkBF. These physiological responses develop sleep architecture and ensure a continuous decrease in T c during nocturnal sleep although T c was to some extent influenced by varying ambient temperature as demonstrated by Dewasmes et al. (1994, 1996), Togo et al. (2007) and Wakamura and Tokura (2002). As opposed to aforementioned circadian regulation before and during nocturnal sleep, not much circadian effect may be expected to maintain the diurnal rhythm of T c during the daytime, particularly in the afternoon. "
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