Group 1 - The concept of "Sanfu Tian" is associated with the peak of Yang energy in nature, making it an ideal time for health practices like "sunbathing the back" to enhance Yang energy and dispel internal cold [1][3] - "Sanfu Tian" is recognized as a prime period for eliminating dampness, with traditional Chinese medicine suggesting that summer heat and increased sweating can lead to more exposure to wind and cold, necessitating special attention to dampness removal [1][3] - The practice of "natural moxibustion" through sunbathing the back has gained popularity, as it utilizes sunlight instead of burning moxa, being referred to as "free moxibustion" [1] Group 2 - Experts indicate that sunbathing the back is particularly beneficial for individuals with cold and damp constitutions, characterized by symptoms such as cold intolerance, cold extremities, and chronic fatigue [3] - Certain populations are advised against sunbathing the back, including those with skin conditions like lupus or psoriasis, children under 14, pregnant women, and individuals with hypertension, hyperlipidemia, or diabetes [3][4] - Precautions are necessary during sunbathing, such as avoiding sunburn, selecting appropriate times for exposure, and limiting sessions to no more than 30 minutes to prevent dehydration [4]