I’ve been very impressed with Sleep Mode in Windows 7. It shuts down quickly and powers down almost completely. No fans and no lights – save a little blinking power light to indicate that your machine is in fact sleeping and not off. Powering back up is almost instant with my monitors taking longer to come back on than my machine.
But I’ve noticed that my machine wakes up occasionally. In the middle of the night. Tossing and turning. I’ll come in to see it all lit up, chugging along. All this without any keyboard or mouse movement. Enter the “wake timer” …
This was my culprit. In my case, while I didn’t have Windows automatically downloading updates in the middle of the night, I did have it checking to see if any are available. Because my “wake timer” setting was enabled, every time this timed event was scheduled to happen (3:00am in my case), my machine would wake up.
The wake timer setting is in the advanced power settings area. Disabling it was all I needed to do to get a good night’s sleep.