Everyone has one of those days where you wake up after a long restful night of slumber and believe that you will finally be well-rested today. You forfeit their spot on the line at Starbuck's and feel prepared for the day. And then you walk into office or classroom and, after a couple of hours, despite the long repose, you feel exhausted. Is it boredom? Maybe, but scientists also say that it may just be the amount of carbon dioxide in the room that is causing fatigue and other health problems.

Outside, typical carbon dioxide concentrations are about 380 parts per million. But, in office spaces, that number can rise to 1,000 parts per million. In classrooms, the number can be as high as a whopping 3,000 parts per million. For comparison, federal guidelines state that carbon dioxide exposure cannot be over 5,000 parts per million for eight hours in an occupational setting.

The reason that the number is so high in these settings is because there are a large number of people exhaling in a confined space. The problem is, according to a paper by the Environmental Health Perspectives, that sustained exposure can have an effect beyond just your energy level. It can also affect your ability to make smart decisions and to think strategically.

Researchers from the State University of New York and the Lawrence Berkeley National Laboratory examined how different levels of carbon dioxide affected people. They took 22 adults, mostly college students, and divided them into six groups. The groups were placed in rooms for two and a half hours that had different carbon dioxide concentrations: 600 parts per million, 1,000 parts per million, and 2,500 parts per million. In each concentration, participants completed a computer test that examined their decision-making skills.

Compared to their ability in the 600 parts per million environment, participants' ability to complete the test declined in six of nine areas examined. Their ability declined further when they were in an environment with 2,500 parts per million of carbon dioxide. Specifically, participants' scores for initiative and basic strategy plummeted.

The researchers say that, if other studies are able to confirm their findings, office buildings and schools should make efforts to improve ventilation systems.

But of course you knew that already. It's just that the carbon dioxide was hampering your ability to realize.