Welcome to Xylem Wellness Systems, Co founded by Dr. Nick Harrell. Xylem gives high-performing men a private, physician-led health system built around their own biology — real diagnostics, real lab work, and a strategy built around the life you actually have, not a generic plan that assumes you have three hours a day to give it.
Dr. Harrell spent over a decade practicing emergency medicine, including the COVID years, when he was pulled into overtime shifts running ICU-level care for some of the sickest patients in the hospital. That’s what convinced him modern medicine is built to manage disease, not build vitality — and it’s why he founded Xylem to practice differently: labs reviewed line-by-line, a protocol built around your own biology, and a physician who treats you like his patient, not a chart. As he puts it: “We’re creating vitality, not treating disease.”
Qualifications
Bachelor of Applied Science(Psychology)
Graduate Diploma of Psychology (Advanced)
Master of Applied Psychology (Clinical)
Doctor of Philosophy (Clinical Psychology) – current
Professional associations and memberships
AHPRA registration: PSY0002268469
Publications
Demmer, D. H., & Tatnell, R. (2025). Readiness assessments prior to gender-affirming medical care: The processes and perspectives of Australian healthcare practitioners. International Journal of Transgender Health, 1–16. Link here
Tatnell, R., Constanti, A., Johansen, S. W. F., & Demmer, D. H. (2025). A mixed-methods pilot study assessing adaptations to the ESTEEM program for Australian same-sex-attracted men. Australian Psychologist, 1–12. Link here
Joint United Nations Programme on HIV/AIDS (UNAIDS). (2024). Chemsex Toolkit for clinical service providers in the Asia-Pacific region. UNAIDS. Link here
