I think it’s more like half that. So 100 mg of caffeine (one cup of coffee more or less) at 6PM is the equivalent of 50 mg (two cups of black tea) at midnight.

I think it’s more like half that. So 100 mg of caffeine (one cup of coffee more or less) at 6PM is the equivalent of 50 mg (two cups of black tea) at midnight. A coffee at lunch (100mg @ noon) is 50 mg by six and 25mg by midnight. Still not great, but a 12 hour half life would likely mean no one would start drinking coffee because you’d never be able to sleep while building up a tolerance.