In recent years, Finnish researchers have conducted an exploratory study on the effects of Water-Filtered Infrared-A (wIRA) on mood. The purpose of this study was to investigate whether a single exposure of wIRA to the skin, without inducing whole-body hyperthermia (WBH), could produce positive mood-improving effects, and to examine whether this effect varies according to individuals' chronotype preferences.

Research Methods

Irradiation Equipment: Wavelength 550–1350 nm; Power 102.4 W; Total dose 123 kJ; Irradiation area 0.0483 m².

Irradiation Site and Duration: Skin on the back and buttocks irradiated for 20 minutes.

Mood Assessment: 40-item Profile of Mood States (POMS) questionnaire.

Chronotype Assessment: 6-item Morningness-Eveningness Questionnaire (mMEQ).

Temperature Monitoring: Core body temperature measured 30 minutes before irradiation, during irradiation, and 30 minutes after irradiation. Skin surface temperature measured every two minutes from baseline throughout irradiation.

Research Results

Total Mood Disturbance (TMD) Score

After irradiation, TMD scores showed significant improvement. The positive effects persisted for 24 hours (p = 0.001) and remained detectable for up to two weeks (p = 0.02).

Differences in Response Between Chronotype Groups

Both morning-type and evening-type individuals experienced noticeable mood improvements. Among evening-types, positive effects lasted for 24 hours (p = 0.022), while among morning-types, improvements persisted for up to two weeks (p = 0.034).

Significant Reduction in Tension and Fatigue

Both tension and fatigue levels showed marked reductions following irradiation.

Changes in Core and Skin Temperatures

Core body temperature decreased from baseline during irradiation. Additionally, morning-type individuals exhibited lower core temperatures than evening-types. The surface temperature of the back skin peaked approximately 10 minutes into the irradiation session before gradually declining.

This study is the first to reveal the potential of infrared-A radiation, applied transdermally and without inducing whole-body hyperthermia, to influence mood.

LifeSun High-Energy Infrared Therapy Device

The LifeSun High-Energy Infrared Therapy Device adopts advanced filtration technology that effectively removes wavelengths responsible for intense thermal effects on the skin while retaining wIRA (590–1400 nm) — a range of wavelengths both tolerable and beneficial to the human body. This allows for penetration of over 70 mm into subcutaneous tissue, providing a gentle, comfortable, and warming experience.