At 13:40 1999-10-06 +0200, Amadeus wrote:
>Possibly by additional detoxifying capacity of the liver.
>Coffee hasn't the equal strong effects after getting used to it.

Getting used to coffein is another thing. It's certain receptors
in the nervous system that get blocked by coffein, this is why
You feel more alert. But quite soon there will be more receptors
to adjust, so You need more coffee a. s. o.

- Hans