Testosterone is an androgen that helps generate the biological characteristics associated with male sexuality. Its effects begin in fetal development, when genes on the Y chromosome trigger testicle development around week 7. Ipamorelin (2mg): The Growth Hormone Peptide For Recovery, Performance, And Longevity Low Testosterone in Men: My Approach to Diagnosis and Treatment OptimalSelf MD But often, there is more going on beneath the surface. Chronic stress can keep cortisol elevated, while testosterone naturally begins to decline with age. That combination can affect energy, mood, sleep, recovery,