According to recent studies, people are smartest in temperatures below 72 degrees Fahrenheit. Anything hotter than that, and thinking suffers. Why do we struggle to think clearly in hotter temperatures? The answer comes down to available energy resources.

Glucose, The God Of Energy

Most people are metabolically adjusted to burn glucose as their primary fuel source. All of your organs, including the brain, use glucose to function. Whether it’s mental processes or physical activities, you need glucose to do it.

Even suppressing emotional responses burns glucose. At any given time, you have a limited supply of glucose. Once it runs low, brain fog begins, fatigue sets in, and it becomes harder to control impulses.

Temperature Regulation Sucks Up Resources

One of your body’s most critical functions is regulating body temperature. Your organs are a lot like Goldilocks. They don’t like their environment too hot or too cold. When your body gets hot, you need to exert energy to cool it down.

Maintaining a healthy internal temperature in hot weather burns a lot of glucose. Cooling the body down uses more energy than warming it up.

Warm Temperatures Hog All The Glucose

Warmer temperatures can cause your body to use up all the available glucose. When there’s no more glucose to go around, the brain slows down. One lab study had participants proofread an article in either a 77-degree room or a 67-degree room. Both seem like reasonably pleasant temperatures, but the warmer room led to significantly worse performance.

Participants in the warm room missed 50% of the errors, while participants in the colder room missed only 25%. A study conducted by Amar Cheema of the University of Virginia and Vanessa M. Patrick of the University of Houston found that sales of scratch tickets in St. Louis County fall by $594 with every 1° Fahrenheit increase in temperature.

In warmer weather, it’s harder to think clearly and make decisions, even ones as simple as buying a lotto ticket. The body burns glucose fast, leaving nothing left over for the brain to work with.