The Nature of Intellectual Performance

Optimal intellectual performance - what are the conditions that guarantee this? Adequate sleep, nutrition and exercise can result in very high mental performance, but is this always a practical goal? For various reasons, all three, sleep, nutrition and exercise can be impaired.

We might think that there are two types of thinking: thinking about things involving a large number of variables and thinking about very narrow, specialised problems. In the first category, the mental activity of "structuring" and "social thinking" (here defined as seeing something from someone else's perspective) can be difficult for someone specialised in the latter. However, too much of the latter can impair performance in the former.

Another interesting question is do people use more of their brainpower in certain activities rather than others? And does the brain's energy consumption (20% of the body's energy) increase for more mentally challenging tasks? Does too much physical activity impair mental performance due to more energy being diverted to the body's physical systems?

Dehydration in extreme circumstances can result in delirium. Delirium may manifest itself in "difficulty completing a single purpose-oriented task - to the extent that a delirious individual may engage in a string of incomplete and unrelated activities". Delirium is a form of organ dysfunction where the organ concerned is the brain. It can be caused by illness, or lack of food, water or sleep.

Dehydration also plays a role in mental performance. It seems there is a critical level of 2%dehydration when impairment to mental and motor performance becomes statistically significant. Water consumption when dehydrated can lead to an "alerting" or "revitalizing" effect (source: Water UK) but overconsumption can result in impairment. Dehydration can occur from exercise, exposure to heat or both. The impact of dehydration is greater on older people.

There is also a connection between food and mental performance. Eating a meal can cause a fall in mental and physical performance, a phenomenon known as the post-prandial dip. This is due to the body diverting energy to digest and absorb the meal.

Interesting article here.