Nervous System 101
Cortisol
Cortisol is often called the body's main stress hormone. It is released as part of the stress response to keep you alert and to free up energy, and it also helps regulate everyday functions like your sleep-wake rhythm. In short bursts it is helpful; the trouble comes when stress keeps it elevated for long stretches.
What cortisol does
Cortisol is a hormone produced by the adrenal glands. During a stress response it rises to keep you alert, free up energy, and sustain the body's readiness after the initial surge of adrenaline has faded. It is the slower, longer-acting part of the stress cascade.
It is not only a stress chemical, though. Cortisol follows a daily rhythm, usually higher in the morning to help you wake and lower at night, and it plays a part in many ordinary functions. It is a normal, necessary hormone, not something to be eliminated.
Why it matters for feeling wired
The problem is not cortisol itself but sustained, elevated cortisol. When stress keeps arriving and the system never fully resets, cortisol can stay higher than it should for longer than it should, which is associated with feeling on edge, sleep trouble, and that wired-but-tired state.
This is why calming the stress response matters. Helping the nervous system come back down, through slow exhales, rest, and lower daily pressure, gives cortisol a chance to return to its normal rhythm rather than staying stuck high.
Sources & further reading
The reputable organizations our editorial team draws on for the anatomy, definitions, and safety guidance behind this page, and where you can read more on each topic.
General educational information about stress and the nervous system. Not medical, dental, or psychological advice, and not a substitute for diagnosis or treatment by a qualified professional.