I have tried experimenting with "sleep" mode, aka Stand By. As far as I can tell:
If I put it into Stand By and then close the cover, it wakes up.
If I put it into Stand By and wait minutes before closing the cover, it doesn't wake up. However, when I open the cover an hour or so later, I have to hit the power button to wake it up. Hitting keys or clicking the mouse doesn't do it. This means that the whole point of my putting it into Stand By, e.g., so that I do not have to hit the power button, is lost.
Not all Windows boxes work this way. I think that mneme's is set differently, and I think that his laptop is technically a Windows box.