1 · Chronic stress · HPA overactivation
Chronic stress keeps the axis switched on and cortisol high, and high cortisol pushes the sex hormone axis down so testosterone synthesis falls.Chronic stress (sleep deprivation, overtraining, psychological stress) → sustained axis activation → chronically elevated cortisol. High cortisol:Suppresses hypothalamic GnRH → reduced / pulses → reduced testicular testosterone synthesisPromotes muscle breakdown, visceral fat accumulation
This chain is directly measurable in humans, and the stress does not have to be dramatic: give healthy young men one week of 5 hours of sleep a night and daytime testosterone falls 10-15%.
So this is not 'low T' needing — it is the stress axis suppressing the sex hormone axis. The direction matters: if the suppression comes from stress, the thing to address is the stressor, not to pour hormones or supplements into the downstream end.