Everyone in business has heard of the summer productivity slump, but what's behind it? Is it simply that too many people are away on vacation to really get anything done? Or that sunny days sparkling outside office windows are too distracting? Maybe it's just the morning-after sluggish of all those fun summer barbecues?

Those are all decent possibilities, but apparently something more fundamental is also at work. It's not just you: Hot weather really does make you lazy and less productive. And there's a simple scientific explanation for why that is so, according to a reassuring recent explainer from Quartz's Katherine Ellen Foley. She writes:

Hot weather actually slows your body down. The hotter it is, the more energy you need to expend to keep yourself cool, which can mean activities you're used to doing easily--whether it's walking around outside or exercising at a certain intensity--take more effort.

How long can I use this as an excuse?

If you can barely rouse yourself to complete even basic tasks once the thermometer climbs high up into the 80s, this is reassuring news. Your boss or customers probably won't accept the excuse that you're simply too warm to be productive (especially given the downright polar conditions in some air conditioned offices), but at least you can tell yourself you're not just suddenly way lazier.

However, this explanation has a definite expiration date, according to Foley. If the heat keeps up, our bodies quickly get used to it. "After only a day or two in the heat, we start producing more plasma, the liquid portion of our blood," she writes. "Not only does this bring more oxygen to the muscles (which they then use to generate energy), it also helps regulate body temperature."

After two weeks in the heat, your body should be fully adjusted. (Though as someone who lives in a place where it's well over 100 most days for months, I've personally found there is some level of heat that there's no getting used to.) But be aware, the "it's just too hot to work" excuse isn't a once-and-you're-done-type deal. Heat acclimatization quickly wears off when the temperature falls again, making this a valid explanation for at least short-term laziness year after year.

"Next time you're back in the heat, you'll be moving like molasses until you can adapt again," Foley memorably notes. Check out her complete article for more details on the body's response to heat, as well as info on how it affects athletic performance.

Do you find your productivity tailing off once the temperature climbs to a certain point?