Periocular skin warming elevates the distal skin temperature without affecting the proximal or core body temperature

Tomohisa Ichiba,Masahiro Suzuki,Sayaka Aritake-Okada,Makoto Uchiyama

doi:10.1038/s41598-019-42116-x

Tomohisa Ichiba, Masahiro Suzuki + Show 2 more

Open Access

https://doi.org/10.1038/s41598-019-42116-x

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Abstract

Periocular skin warming reportedly improves the objective and subjective sleep quality in adults with mild difficulty in falling asleep. To clarify the effects of periocular warming, we examined the distal skin temperatures (hands and feet), proximal skin temperature (infraclavicular region) and core body temperature as well as the distal-proximal skin temperature gradient (DPG). Nineteen healthy males underwent two experimental sessions, wherein they used a warming or sham eye mask under a semi-constant routine protocol in a crossover manner. Participants were instructed to maintain wakefulness with their eyes closed for 60 minutes after wearing the eye mask. The warming eye mask increased the periocular skin temperature to 38–40 °C for the first 20 minutes, whereas the temperature remained unchanged with the sham mask. Compared to that of the sham eye mask, the warming eye mask significantly increased the temperatures of the hands and feet and the DPG, whereas the proximal skin and core body temperatures were unaffected. Subjective sleepiness and pleasantness were significantly increased by the warming eye mask. These results represent physiological heat loss associated with sleep initiation without affecting the proximal skin or core body temperatures, suggesting that thermal stimulation in certain areas can provoke similar changes in remote areas of the body.

Highlights

Sleep is reported to be closely related to the circadian rhythm of the core body temperature (CBT)[1,2]
Participants were instructed to maintain wakefulness with their eyes closed for 60 minutes after wearing the warming or sham eye mask in a crossover manner
Polysomnographic (PSG) recordings, including electroencephalography (EEG), electrooculography (EOG), and electromyography (EMG), were scored at every 30-s period during the observation period, and the participants were determined to be in the stage wake according to standard criteria, which ensured that the maintenance of wakefulness was successful in the present experimental procedure

Summary

Introduction

Sleep is reported to be closely related to the circadian rhythm of the core body temperature (CBT)[1,2]. The circadian rhythm of the CBT is modulated by heat production and loss via the distal skin temperature[3,4]. Previous studies have indicated that manipulation of the skin or body temperature can enhance or disturb sleep in humans[7,8,9]. Pharmacological studies have revealed that administration of melatonergic agents[13,14] and benzodiazepine hypnotics[15] enhances heat loss via distal skin regions and induces sleep. Direct warming manipulation of the skin temperature and hypnotic drug administration are likely to modulate sleep by controlling heat loss processes for skin regions. Fingers[20] may indicate that periocular skin warming influences sleep through a similar heat loss process via distal skin regions, as reported in previous clinical and intervention studies. We aimed to find differential effects of periocular skin warming on the distal and proximal skin and core body temperatures

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