Ok, you’ve had two glasses of wine with dinner and it’s time to head home. You feel fine, but throw down a couple of cups of coffee to clear your head just to be sure. Then you pay the bill, walk out to your car, get behind the wheel — and one block after pulling out of the parking lot you see flashing red lights in your rear view mirror.
A couple of minutes later you find yourself struggling to walk heel-to-toe on a straight line. Well, you think, I only had a couple of drinks. A couple of drinks — and coffee….
Field sobriety tests are used by officers as evidence of whether an individual is under the influence of alcohol or not. These commonly involve such excercises as "walk-and-turn", "finger-to-nose" and "one-leg-stand". The greater the intoxication, in theory, the worse will be the performance on these tests.
However, the truth is that these "tests" are highly unreliable and subject to such variables as the individual’s age, weight and athletic ability, the conditions under which the tests are given, the emotional state of the individual, fatigue, unfamiliarity with the tests, proximity to passing traffic, failure of the officer to communicate instructions, and many others.
And then there is caffeine…..
Caffeine and alcohol have a synergistic effect — that is, they combine to produce an accelerated effect. Rather than sobering a person up, as is commonly believed, coffee can actually increase the symptoms of alcohol.
The definitive studies were done by researchers in Great Britain and reported in an article entitled, "Interactions of Alcohol and Caffeine on Human Reaction Time", appearing in the scientific journal Aviation, Space and Environmental Medicine 528 (June 1983).
The conclusions of the scientists:
"Alcohol has always been categorized as a central depressant and caffeine as a central stimulant. Therefore, it should follow that an antagonistic [counter-active] interaction should occur when these two drugs are ingested simultaneously. But as these results illustrate, this is not necessarily the case…
"Caffeine has a synergistic interaction with alcohol…(It) has the effect of potentiating the detrimental effects already induced by alcohol….Motor skills which involve delicate muscular coordination and accurate timing have been found to be adversely affected by caffeine."
Result? Poorer performance on the field sobriety tests — and an arrest for DUI.