It’s nice to have a coffee after a meal out, especially if you’ve had a few glasses of wine. But although it may feel like the caffeine perks you up, it might not have any impact on how sober you are.

In the Channel 4 program Food Unwrapped, Tony Moss, a professor of addictive behaviour science at London South Bank University, said coffee does not help decrease blood alcohol levels. This means functions affected by drinking such as hand-eye coordination and reaction time will still be hindered — even though you might feel more alert from the caffeine.

Moss recruited five students to drink a vodka and tonic, which was the right measure for their size to make them feel the effects of the alcohol. Then, they were told to complete a test of guiding a metal hoop around a wire without them touching, to see how their hand-eye coordination was faring.

They all failed the test. And they failed again after drinking a cup of coffee. Breathalyser tests showed their alcohol levels had not been impacted by the coffee either.

The only way to actually sober up, Moss said, is to wait it out.