Sweating is primarily regulated by the sympathetic nervous system, which is part of the autonomic nervous system controlling involuntary bodily functions. The sympathetic nervous system uses the chemical messenger acetylcholine to activate sweat glands. While hormones like epinephrine (adrenaline) and norepinephrine (noradrenaline) can trigger sweating in response to stress or physical activity, they are not directly responsible for the actual process of sweat production.
In short, the hormone responsible for sweating is acetylcholine.
