Apparently, you can't judge activity by outward evidence.
Intuitively, it makes sense that we're willing to wait and do nothing than do something for no reason - it conserves energy. So sure, it's human nature to be lazy, unless there's a good reason to be active.
Imagine you're entering the line for a cool new ride at the amusement park. The line moves fast so you spend five minutes walking back and forth until you get to the ride. When you get there, you have to wait one minute for the cars to return to the station. How impatient do you feel as you wait, first in line to board? Not very, right? You've been active, making progress, and you have a pretty short wait. No big deal.
Now contrast that with this: you're entering the line for a cool new ride. Hardly anyone is there and it only takes a minute to get to the front of the line. But then you have to stand there waiting five minutes while a ride engineer checks a safety strap on a car that isn't being used. How impatient are you? You're stuck doing nothing, and you're a little irritated.
As it turns out, if time is available, we love to fill it with activity. Parkinson's Law (1955) says that "work expands so as to fill the time available for it's completion." But even at the oddest of times, when our bodies can't be active, our brains still are. During sleep, for example.
Long ago in the dark ages (pretty much anything before the 70's or 80's), brain imaging showed that human brains weren't as active when their people were asleep as when they were awake. Well, those early studies weren't very extensive or accurate, as it turns out. Now we have fMRI. And with that, and EEG, we now know two things. First, the old stuff is true, sometimes. About five or six times a night, specifically. Our brains are indeed less active during REM sleep (when we're dreaming) than when we're awake. But second, our brains are more active during non-REM sleep - in several areas. (Cerebellum activity is highlighted in the above photo.)
These periods of brain activity are really busy. In fact, the level of activity is nearly the same as when we're awake and actively involved in some task. And it's during this time that our brains sort out garbage from important stuff, and file away the important stuff in long-term memory.
And how busy is busy? You can't accurately compare the human brain to a computer, in terms of processing speed, but this will give you some idea. The brain can process about ten one-million-point images per second from one retina. The brain itself has the neurons to handle 100,000 times that much information, so that works out to be roughly 100 million MIPS (Million computer Instructions Per Second). That's about like a 168,000 MHz Pentium processor - or more than 20 times my quad core. Of course this is a rough comparison
Is this meeting really boring or really productive?
Mind working overtime? Maybe not.
Uh, never mind.
You know those mornings when you wake up and feel even more tired than when you went to bed? Maybe your brain had an incredibly busy night. Call work, tell them you'll be late, and go back to bed. I'll write you a note. :)