And did it lead to any treatment or other changes that helped? A friend just had the test done with a specialist. She gave me this description: two independent clinical tests (or studies) designed to determine the ability of both branches of the autonomic nervous system (ANS) to respond to and relax from a challenge. The two branches that make up the ANS are the sympathetic and parasympathetic (SNS and PSNS, respectively). The challenges are: 1) deep breathing to challenge the PSNS, 2) valsalva to challenge the SNS, and 3) standing from a seated position to challenge both systems.