Sydney Peterson grew up in Lake Elmo, Minnesota, and attended the same high school as American cross-country skiing legend Jessie Diggins. She was a four-sport athlete in high school, participating in Nordic skiing, swimming, cross-country and track. At 13, Peterson began experiencing symptoms of primary dystonia in her left arm — neurological disorders that caused involuntary muscle contractions and chronic pain. Over time, the dystonia progressed, affecting the mobility in both her left arm and leg.

Six years later, Peterson would compete for the first time at the 2021 World Para Snow Sports Championships, delayed until January 2022, and won three medals. Two months later, she made her Paralympic debut at the Paralympic Winter Games Beijing 2022. Peterson would go on to win three medals in cross-country skiing, including a gold as a member of the U.S. mixed relay team.

In 2023, Peterson would undergo an invasive brain operation where an electrode was implanted into her brain and connected to a battery pack in her chest, known as deep-brain stimulation. The operation was a way to reverse the worsening effects of her dystonia, but also required her to be awake for 13 hours during the procedure. She returned and won two more medals at the 2025 world championships. 

Off the snow, Peterson graduated from St. Lawrence University in 2023 with a bachelor’s degree in neuroscience and is now pursuing a PhD in neuroscience at the University of Utah, balancing her research with her training.