Effect of Earthing Mats on Sleep Quality in Rats

Abstract

Grounding, a therapeutic technique involving direct contact with the earth, has been proposed by various studies to potentially have beneficial effects on pressure, sleep quality, stress, inflammation, and mood. However, the scientific evidence supporting its sedative effects remains incomplete. This study examined the sedative effectiveness of an earthing mat on sleep quality and investigated the underlying neural mechanisms using electroencephalography (EEG) analysis in rodents, focusing on orexin and superoxide dismutase (SOD) levels in the brain. Rats were randomly assigned to four groups: the naïve normal group (Nor), the group exposed to an earthing mat for 7 days (A-7D), the group exposed to an earthing mat for 21 days (A-21D), and the group exposed to an electronic blanket for 21 days (EM). EEG results revealed that the A-21D group exhibited significantly reduced wake time and increased rapid eye movement (REM), non-rapid eye movement (NREM), and total sleep time compared to the Nor group (p < 0.05). Moreover, the A-21D group demonstrated a significant increase in NREM sleep (p < 0.001), REM sleep (p < 0.01), and total sleep time (p < 0.001), along with a decrease in wake time compared to the EM group (p < 0.001). The orexin level in the A-21D group was significantly lower compared to the Nor group (p < 0.01), while SOD1 expression was markedly elevated in the A-21D group compared to the Nor group (p < 0.001). These results suggest that the earthing mat may represent a promising new method for promoting sleep quality and could serve as an effective therapeutic technique.

Keywords: SOD1; earthing mat; electroencephalography (EEG); orexin; sleep disturbances.

Figure 1

Effect of earthing mat on sleep architecture. Changes in the percentage of wake time (A), REM sleep (B), NREM sleep (C), and total sleep (D) during the dark phase are depicted in the earthing mat-exposed groups. The data represent the mean ± SEM of the percentage of time spent in the sleep–wake state. *** p < 0.001, * p < 0.05 vs. Nor, ### p < 0.001, ## p < 0.01 vs. A21-D; one-way ANOVA followed by Tukey. ● Nor, ■ A-7D,▲ A-21D,▼EM.

Figure 2

Impact of earthing mat on orexin-positive cells in the LH. (A) Photomicrographs illustrating orexin-positive cells in the LH. The dashed circles indicate the LH region. (B) Quantification of orexin-positive cells in the LH. *** p < 0.01 vs. Nor; ### p < 0.05 vs. A-21D; one-way ANOVA followed by Tukey’s test.

Figure 3

Impact of earthing mat on SOD-positive cells in the LH. (A) Photomicrographs illustrating orexin-positive cells in the LH. (B) Quantification of SOD-positive cells in the LH. *** p < 0.01 vs. Nor; one-way ANOVA followed by Tukey’s test.

Figure 4

Animal groups and treatments in the experimental design of this study.