The concept of transcendental (trance) states, also known as altered states of consciousness, has existed since ancient cultures with religious rites, ceremonies, prayers, meditation, yoga, etc. Because of the mysterious nature of consciousness, for a long time, altered states of consciousness have been characterized by opposing scientific stances and theoretical explanations. Only in the last decades, neuroscientific studies have determined that altered states of consciousness (such as rituals, hypnosis, breathwork, meditation, out-of-body experiences, near-death experiences, and the lucid dreaming state) share common neurocognitive characteristics such as lower perceptual boundaries, lack of reflective awareness, detachment from reality, feelings of relaxation and passivity. This book provides a comprehensive examination of the literature on altered states of consciousness, following with a detailed analysis of hypnosis, near-death experiences, and meditation, their scientific status as trance states, and their empirically supported benefits in treating anxiety disorders and enhancing well-being. The aim of this research work is thus to determine whether meditation and relaxation techniques can significantly improve stress and anxiety symptoms among young adults. For this purpose, a randomized experimental design was implemented to test the efficacy of guided meditation and deep breathing as mindfulness techniques in comparison to music relaxation (control condition) on anxiety levels (i.e., cognitive anxiety, somatic anxiety, systolic and diastolic blood pressure, heart rate, and self-esteem) among thirty-three university students in Albania. The intervention was carried out over four days, and the results showed that all groups (experimental and control) showed improved symptoms of anxiety, with guided meditation and deep breathing improving the majority of anxiety symptoms (systolic and diastolic blood pressure, heart rate, and cognitive anxiety). Despite some limitations, these findings provide important theoretical implications for the mindfulness and meditation literature, as well as practical implications for the use of mindfulness techniques as effective treatments for stress and anxiety management and well-being enhancement.