Oriental arborvitae (Platycladus orientalis, also known as Thuja orientalis) seeds, commonly called "Bai Zi Ren" in traditional Chinese medicine (TCM), have been used for centuries as a calming agent, particularly to address symptoms such as anxiety, insomnia, and palpitations. Traditional texts like the Shennong Bencao Jing and subsequent materia medica describe Bai Zi Ren as nourishing the heart and calming the spirit ("shen"), which is linked in TCM to emotional disturbances including anxiety.

Modern scientific research on the anxiolytic (anxiety-reducing) properties of oriental arborvitae is limited. Some animal studies have explored extracts of Platycladus orientalis seeds, suggesting potential sedative and anxiolytic effects, possibly due to compounds like lignans and essential oils. However, these studies are preliminary, often lack rigorous controls, and have not been widely replicated or confirmed in human clinical trials. No high-quality, large-scale randomized controlled trials have validated its efficacy or safety for anxiety in humans.

Therefore, the use of oriental arborvitae for anxiety is primarily justified by a long history of traditional use rather than strong scientific evidence. While some promising preclinical data exist, the overall evidence rating is low due to the lack of robust clinical research. Individuals interested in using this herb for anxiety should consult healthcare professionals and consider the limitations of current evidence.