norepinephrine
Norepinephrine (also called noradrenaline) is a neurotransmitter produced by the locus coeruleus in the brainstem. It regulates alertness, attention, arousal, and the stress response, and works alongside dopamine in the prefrontal cortex to support executive function. Your prefrontal cortex needs norepinephrine in an optimal range — too little, and you can't sustain focus, too much, and the brain shifts to reactive, survival-oriented processing.
In ADHD, norepinephrine signalling is dysregulated, contributing to difficulties with sustained attention, emotional regulation, and the stress response.



