Pot Pourriddle #1

I’m not a button but am pressed,
Raise your heart rate when at rest;
I drip so you don’t drop,
Stimulate so you don’t stop;
I’m not beer but can be brewed,
Dark as night when in the nude;
Make me heavier I get lighter,
Through a filter life gets brighter,
I am ready in an instant
But take longer under pressure.
What am I?