The other issue here is the term tolerance. There's the "I have a high tolerance" sentiment from people who think that means they can drink a couple more drinks than their friends and not pass out verses real tolerance in the medical sense of the term. Tolerance in the medical sense is that you have submerged your central nervous system in a depressant for so long that it has effectively "Overclocked" itself to compensate. It now runs faster and hotter in order to overcome the constant presence of something trying to slow it down. That's why people with real tolerance sweat profusely, have uncontrollable shaking and potentially seizures and hallucinations when the CNS depressant is removed from their system. Their nervous system has adjusted to only function normally with the depressant in their system and functions extremely abnormally without it.