The Study
Cortisol-induced suppression of plasma testosterone in normal adult males.
This study noticed that when people had more cortisol, their testosterone seemed to drop. But it didn’t test it like a science experiment — it just watched what happened. So we can’t say cortisol definitely caused the drop, just that they often happened together.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
When the body gets a lot of cortisol (a stress hormone), it stops the normal nighttime boost in testosterone.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 520 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this means high stress could lower testosterone levels at a key time of day, potentially affecting energy, mood, or muscle recovery.
- 2Cortisol flattened or removed the normal nighttime rise in testosterone.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
The Journal of clinical endocrinology and metabolism
Year
1975
Authors
P. Doerr, K. Pirke
Related Content
Claims (2)
When cortisol is administered at levels naturally produced during stress, it reduces testosterone levels in adult men by preventing the normal nighttime increase in testosterone.
Higher levels of the stress hormone cortisol cause the pituitary gland to release less luteinizing hormone, which results in lower testosterone production by the testes.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.