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Effects of far-infrared radiation on heart rate variability and central manifestations in healthy subjects: a resting-fMRI study


The aim of this study was to investigate the autonomic responses and central manifestations by peripheral FIR stimulation. Ten subjects (mean ± SD age 26.2 ± 3.52 years) received FIR stimulation at left median nerve territory for 40 min. Electrocardiograph was continuously recorded and heart rate variability (HRV) were analyzed. By using a 3 T-MRI scanner, three sessions of resting-state functional magnetic resonance images (fMRI) were acquired, namely, before (baseline-FIR), immediately after (IA-FIR) and 15 min after FIR was turned off (Post-FIR). The fractional amplitude of low-frequency (0.01-0.08 Hz) fluctuation (fALFF) of each session to evaluate the intensity of resting-brain activity in each session was analyzed. Our results showed that FIR stimulation induced significant HRV responses such as an increasing trend of nLF and LF/HF ratio, while FIR increased fALFF in right superior front gyrus, middle frontal gyrus and decreased the resting brain activity at fusiform gyrus, extrastriae cortex, inferior temporal gyrus and middle temporal gyrus, especially 15 min after FIR was turned off. We conclude that the central manifestation and the autonomic responses are prominent during and after FIR stimulation, which provide important mechanistic explanation on human disorder treated by such energy medicine.

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Far-infrared radiation


Heart rate variability


Functional magnetic resonance imaging


Fractional amplitude of low-frequency fluctuation


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We are indebted to the Laboratory of Integrated Brain Research, Department of Medical Research and Education, Taipei Veterans General Hospital, Taiwan, Republic of China, for their excellent comments and resources. We acknowledge MR support from National Yang-Ming University, Taiwan, which is in part supported by the MOE plan for the top university.

Competing interest

The authors have no competing interest.

Authors’ contributions

Lin YJ conducted the studies, analyzed the data, and wrote the manuscript. Chiu JH supervised Dr. Lin YJ and designed the study. Hsieh JC assisted the study design while KungYY, Kuo WJ, Niddam DM, Chou CC, Cheng CM, and Yeh TC provided facilities and helped to analyze the data.

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Correspondence to Jen-Hwey Chiu.

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Lin, YJ., Kung, YY., Kuo, WJ. et al. Effects of far-infrared radiation on heart rate variability and central manifestations in healthy subjects: a resting-fMRI study. Lasers Med Sci 30, 295–301 (2015).

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  • Far-infrared radiation
  • Heart rate variability
  • Resting state network
  • fMRI