Near Infrared Spectroscopy (NIRS) is a powerful technology used in many areas of medicine, including traditional and innovative medicine. In ancient medicine, NIRS has been used to gain insights into diseases and medical treatments of the past. For example, in traditional medicine, NIRS can be used to determine effects of acupuncture and the quality of herbal medicines. In modern medicine, NIRS is used to diagnose and monitor diverse conditions, including brain injuries, stroke, and cancer. Over the decades, the application of NIRS in neuroscientific and neurological research has gained importance, and the number of scientific studies has grown extensively. Within the current opening lecture, a short review and highlights from 1995 to 2023 from an interdisciplinary research team at the Medical University of Graz, Austria, Europe, was presented. Main topics are among others results from transcranial cerebral oximetry in the hyperbaric environment and the non-invasive assessment of oxygen metabolism using NIRS technology during high altitude trekking in the Nepal Himalayas. In addition, NIRS publications from intensive care medicine and needle and laser acupuncture are presented and discussed. NIRS could be a fruitful approach helping to explore deeper biological mysteries within the brain and the periphery. Overall, NIRS is a powerful tool that has the potential to unlock many mysteries of ancient and modern medicine. As technology continues to improve, it is likely that NIRS will become even more important in the diagnosis and treatment of a wide range of medical conditions.