I doubt that they would. It generally depends on the size of the change though. If the day became 30 hours long, I reckon we would still sleep for a similar amount of time, but would be able to get more done, becoming more productive overall. Schools would probably add on a bit of time, as humans would adapt to the change. As we stayed up for longer, our bodies would become more used to the change, and get more REM sleep out of the 8-10 hours people normally get (Excluding those people who decide they can live off 3-4 hours before school etc) but it would be fine in my eyes.

I really need to learn more about the mechanics of the brain.

To my knowledge, the brain adapts to our cycle over time. Obviously it resists change but we have (not sure where I heard this-- I very well could be wrong, in which case please down vote this comment) an "internal clock" if you will that wakes us up naturally if a constant time is "set."

-

However, we do not truly "wake up" (and by that I mean achieve optimum brain function) until about 10 am (this I am certain of). This is independent from the adaptable consciousness. This cannot be changed as it is thoroughly ingrained into us by way of billions of years of having a constant day/night cycle.

So our sleeping patterns may adjust; however, they are not optimal for our function.

-

Ideally, we should wake up, as I said, around 9:30-10:00. This is not practical in American society, but in France...sure.

I don't think so. People in Alaska have the Midnight Sun and they have adapted to the day's length.