Food, drinks and driving

Human performance at the wheel is susceptible to subtle internal states — how well wired the body and mind are to respond.

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According to physiologist Ralf P. Brandes of the Goethe University Frankfurt’s Institute for Cardiovascular Physiology, two common but underestimated states — feeling overly full, and being hungry or thirsty — can undermine the concentration required for safe driving.

When we arrive at the wheel after a large meal, the body shifts attentional and metabolic resources. Brandes explains that “Being full is one of the main reasons for fatigue. If you treat yourself to a large meal ... you could end up in what we sometimes call a ‘pasta coma’ afterwards.” In effect, your body is busy digesting, blood flow is redirected to the gut, and the high blood-sugar surge leads to a subsequent drop — all of which reduce alertness. On top of that, the warm, relaxed post-meal state induced by digestion leads to a natural lowering of vigilance.