The study protocol for MELLOW has been published in npj Women’s Health. MELLOW, which stands for ME/CFS + Long COVID Longitudinal Omics and Women’s Health, is a Melbourne ME/CFS Collaboration study of how hormonal rhythms relate to symptoms in both conditions.
Hormone levels change across the day and across the menstrual cycle, and most research has sampled patients without accounting for that. MELLOW is specifically designed to measure that change. Blood from sixty women, twenty with ME/CFS, twenty with Long COVID and twenty without either, will be sampled at four points in each menstrual cycle and again when they naturally experience post-exertional malaise, alongside continuous data from wearable devices and daily hormone readings at home.
Publishing the protocol sets out the design before the results exist, so the study can be assessed on how it was built rather than on what it eventually finds. The paper is first-authored by Dr Natalie Thomas, with Dr Chris Armstrong as corresponding author.
We have put together a short explainer on what the study will measure, when samples are taken, and what a study of this size can and cannot answer.
The protocol appeared in npj Women’s Health, 4(3), on 14 January 2026.