If you’re finding yourself unable to keep your eyes open in meetings, your droning co-worker or late night may out may not be the only explanation.

Modern office buildings are often a marvel of efficient design. Cooled to suit-friendly temperatures in even the blazing days of summer, the best of the breed manage to keep workers comfortable while preserving energy efficiency through clever insulation and temperature controls. It’s great for the environment and for your landlord’s heating and cooling bills, but there’s one big downside.

Your office is likely putting you to sleep and impairing your decision making skills.

All those precision seals and crafty conservation measures may keep cool air from escaping, but they are also trapping else in -- CO2. A study last year found that,

While typical outdoor concentrations are around 380 parts per million (ppm), indoor concentrations can go up to several thousand ppm.

Higher levels indoors are usually due to poor ventilation, often a result of the need to reduce a building’s energy consumption, the researchers say… They found that carbon dioxide concentrations in office buildings normally don’t exceed 1,000 ppm, except in meeting rooms, when groups of people gather for extended periods of time. (Which may partly explain why it’s so hard to stay awake in meetings.)

That’s good to know when you need an excuse for your droopy eyelids at a meeting, but according to a recent post on Treehugger, if you have the facts about your office’s CO2 levels, there are steps you can take to keep your office environment from sucking away your energy.

If you’re looking for an automated solution, the post notes that, “the Fraunhofer Institute for Microelectronic Circuits and Systems in Duisburg, Germany… working with the Athmer company, designed a door seal that measures concentrations of CO2. A sensor records CO2 levels, and when a threshold is reached, the seal is opened and the ventilation system kicks in, delivering new oxygen to tired brains.”

But if that level of sophistication seems a bit beyond your reach, the low-tech solution is simply to be aware of the link between CO2 and your impulse to snooze and open the door manually when you feel drowsy. Treehugger offers other quick and dirty fixes: "There are also a host of hand-held CO2 sensors now on the market, some of which will even beep to let you know when levels climb to drowse-inducing. Or, we can all get a CO2-sucking micro-algae lamp on our desk!" Keeping a couple of green plants alive at work can help, as can ensuring you don’t squeeze too many people into a small conference room for long meetings.

Do the meeting rooms at your office make you feel drowsy?