“The caffeine seems to act differently on different people. In my case rarely do I drink a double espresso even late in the evening with dinner that would prevent me from falling asleep. But I know people that would not have sleep for the whole night”
Correct, again its pretty individual. Some people (c10%) can metabolise the caffeine super quick so sleep fine after imbibing. But for most of us, we might APPEAR to sleep fine (ie we’re unconscious) but our sleep architecture is adversely affected so our sleep quality is poor. I can’t overstate how important a decent amount of good quality sleep is for physical and mental health. Just by way of example: one night of poor sleep and your levels of amyloid in the brain rise by 10-15%. High levels of amyloid in the brain are associated with dementia. Poor sleep = increased dementia risk