NoradrenalineNorepinephrine
A stress hormone and neurotransmitter driving arousal, focus and vascular tone.
Noradrenaline acts in two roles: as a hormone from the adrenal glands and as the main neurotransmitter of the sympathetic nervous system. It raises alertness and attention, constricts blood vessels to maintain blood pressure, and mobilises fuel much as adrenaline does.
It matters because it is more about sustained arousal and vigilance than the acute surge adrenaline provides. It is central to attention and to the stress response, and it is the target of several antidepressant and ADHD medications.
In practice it also rises with exercise and cold exposure, and it is the reason a deliberate cold plunge produces a lasting lift in alertness and mood — one of the few effects of cold exposure with a clear mechanism behind it.
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Written and reviewed by Mathew Beale, MSc Biotechnology, University of Reading.
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