Have you ever known someone that you asked a fairly innocent question, like ”Did you ever have a beard?”, and much later you discover their reply was a lie? You wonder, why on earth would they have lied about that? What difference would telling the truth have made? And your opinion of that person slips a bit.
Mostly, telling you the truth, yes they had a beard, in fact a couple of times, wouldn’t have made a difference at all. They are just in the habit of telling lies. They might lie about where they used to live, and you don’t realise because they say it so easily, until someone else tells you where they lived and you just wonder why would they lie?
These people are compulsive liars, or pathological liars. They started to lie when they had low self esteem, and then it became a habit. They know they are telling a lie, they know that the lie may hurt you, but lying is such a habit that they tell the lies.
This is a mental illness. It needs counselling to explore when and why it started, and help to start telling the truth. People like this often have a narcissist personality. Examples are Trump, and Boris Johnson. They are players on the world stage. I would guess that Erdogan in Turkey is one, and Prince Andrew certainly showed signs of narcissism during that appalling interview. And very likely told a pack of lies. There is no c0ndition of not being able a sweat because of an overload of adrenalin.
So the pathological liar starts when self esteem is low, most usually during puberty, because that is when self esteem is most vulnerable. It might be after a trauma, or the death of a family member, particularly a parent. They start to lie because the truth doesn’t seem adequate, or maybe a sibling is doing better. Or they have idolised sibling when there is a wide age gap.
It’s difficult to deal honestly with this person. You don’t realise they are lying but something doesn’t add up. You refer to something they told you and there is no appropriate reaction. They have a mental illness that makes lying the easier option. Even when they know they will be found out. Or they don’t know you happened to see the email alert on the screen of their phone, and later tell you they didn’t get an email that day.