India, Dec. 11 -- Ayurveda has always treated sunlight as a therapeutic force. Practices like Atapa Snana (sunbathing) and Atapa Swedha (sweating through sun exposure) were once common in daily life, believed to strengthen vitality, support the skin's natural rhythms, and build emotional and physical resilience. Today, these ancient customs are resurfacing in wellness spaces under a new name: heliotherapy, the therapeutic use of sunlight for better health and to fight diseases. As vitamin D deficiency becomes more widespread and wellness enthusiasts seek more elemental forms of healing during winter, sunbathing through heliotherapy has unexpectedly reclaimed its place at the centre of holistic well-being. It is the structured use of natural or artificial sunlight for therapeutic purposes. Dr Prateek, consultant at Maccure Hospital, explains, "The sunlight's influence on molecules like melatonin and serotonin creates measurable improvements in sleep cycles, cognitive performance and daytime alertness. It is essentially a way of harnessing these benefits to help people manage chronic fatigue, low immunity, vitamin D deficiency and metabolic imbalances." Dr Prateek says, "Exposure to sunlight supports the immune system by enhancing metabolic health and contributes to overall well-being." Dr Prashant Sinha, head of emergency from PSRI hospital, adds, "Sunlight also supports nitric oxide release, which may contribute to better heart function and blood pressure regulation". According to Dr Prashant, "Sunlight stimulates serotonin, which directly influences mood, energy levels and focus. This is why controlled sun exposure can help with mild seasonal affective symptoms, low motivation and fatigue." This makes heliotherapy a valuable stabiliser for those experiencing mild anxiety or winter-associated seasonal depression. Dermatology has long embraced controlled UV light for treating psoriasis, eczema and vitiligo. Dr Navjot Arora, dermatologist at Dermaheal Skin and Clinic, notes, "Controlled sun exposure benefits the skin in multiple ways when practiced safely. Sunlight triggers vitamin D synthesis in the skin, which supports immunity, reduces inflammation and strengthens the skin barrier". However, she is firm about safety: "Exposure should not exceed 10-20 minutes and must stop at the first sign of redness. Overexposure can harm the skin's barrier, causing sunburns and hyperpigmentation. Even in winter, sunscreen is recommended to reduce pigmentation and early ageing". As heliotherapy resurfaces in wellness culture, retreats are reinterpreting traditional sun-based rituals. Here are the three most popular heliotherapy techniques found in India:...