Endocrine System
The hormone system that quietly regulates growth, metabolism, mood and reproduction.
Glands scattered throughout the body release hormones directly into the bloodstream, where they act as chemical messages read by distant cells. Compared with the nervous system's instant signalling, hormones work on a slower, broader timescale — shaping energy levels, hunger, stress response, sleep-wake timing and reproductive cycles over hours to years.
Key organs & structures
How it connects
Chronic stress keeps cortisol elevated, which can disrupt sleep, appetite and mood.
Resistance training and sleep are two of the strongest natural levers on testosterone and growth hormone.
Deep-dive guides in the endocrine system
Conditions involving this system
Did you know?
- • The thyroid, a gland the size of a walnut, helps set the pace of your entire metabolism.
- • Cortisol naturally peaks shortly after waking as part of a healthy circadian rhythm.