Does your PC not sleep, hibernate or wake up as it should? PassMark Sleeper is a small testing tool which may be able to help.
At a minimum it'll tell you more about the features your PC supports. Launch the program, for instance, and you'll see details on any supported power states (S1, S2, S3 or S4) and whether your system should then be able to wake up on its own afterwards.
Now click Configuration for a host of useful test settings.
You're able to enter "Sleep durations", for instance - the number of seconds your PC should remain awake during testing of each sleep state (30 seconds is the default for S1).
If you find your PC just has occasional sleep issues, try running multiple tests by entering 10 (for instance) in the "Number of cycles" box.
Finally, check "Restart automatically after power cycle", click OK > Sleep Now, and the program will try to make your PC sleep, then reboot after a few seconds, repeating the process for as many times as you've specified, and logging the results.
And if you need more, Sleeper also provides an extensive command line interface, allowing you to put a computer to sleep using your preferred state, sleep time and so on.
Please note, Sleeper is free for personal use only. Businesses must purchase a $15 licence.