Tree Peony (Paeonia suffruticosa, also known as "Mu Dan Pi" in traditional Chinese medicine) has a long history of use in East Asian herbal medicine. Traditionally, it is used for its purported abilities to "cool the blood," clear heat, and support circulation. In some traditional Chinese medicine (TCM) formulations, Tree Peony root is included in formulas designed to address symptoms such as muscle cramps, twitching, and restlessness—symptoms that can overlap with those experienced in Restless Leg Syndrome (RLS). However, it is critical to note that there is a lack of direct historical records or clinical trials specifically validating the use of Tree Peony for RLS as defined in modern medicine.

The rationale for its use in this context is mostly based on TCM theory and the empirical use of formulas aimed at relieving muscular discomfort or spasms. Modern scientific studies specifically investigating Tree Peony root for RLS are lacking. Some preclinical studies have shown anti-inflammatory and neuroprotective effects of Tree Peony extracts, but these findings do not directly translate to efficacy in RLS. Thus, while there is some traditional precedent for its use in related symptoms, robust scientific evidence and clinical validation are currently insufficient.