Phosphatidylserine (PS) is a phospholipid component found in cell membranes, particularly abundant in neural tissue. Its use in supporting the sympathetic nervous system (SNS) is based on its role in modulating stress responses and neuroendocrine function. Scientific studies, mainly in animal models and small human trials, suggest that phosphatidylserine supplementation can help attenuate cortisol responses to acute stress, which involves SNS activation. For example, a 2004 double-blind study by Monteleone et al. found that PS supplementation reduced cortisol and adrenocorticotropic hormone (ACTH) responses to physical stress in healthy males, indicating a dampening of the hypothalamic-pituitary-adrenal (HPA) axis, which is closely linked to SNS activity.

However, while these findings suggest a modulatory effect on stress-related SNS activation, the evidence is limited by small sample sizes, short durations, and a focus on general stress rather than direct measures of sympathetic output (such as heart rate or norepinephrine). Larger, well-controlled trials in diverse populations are lacking. The majority of evidence for PS supplementation is stronger for cognitive health, particularly in age-related memory decline, rather than direct support of the sympathetic nervous system itself. Therefore, while there is preliminary scientific support for PS modulating stress responses involving the SNS, the evidence is modest and not robustly established for direct sympathetic nervous system support.