When you click down the button of sleep, only screen is off but the PC is still running. After rebooting, sleep will work.
Why? Because some process is running and preventing your PC from sleeping. After rebooting the PC, the process will be terminated so that you can sleep the PC.
We can use just one command to find out the process.
Open your CMD or Powershell, and input this command:
Well, we can find that a process named NeatDM.exe is preventing sleeping. It’s a download software. After closing it, I can sleep my PC at once.
Remember, this is for the situation where you sleep your PC but it wakes up at once.
However, sometimes you would face the situation where the PC slept successfully, but it wakes up later for a while. For this situation, you need to use this command to check which device woke your PC up last time:
However, sometimes things get wired. You just see the woke device is Fixed Power Button, but you didn’t press the button! OK, for this strange thing, I find it caused by Wake on LAN. Some devices in your LAN woke your PC up but Windows recorded it as Fixed Power Button.
Finally, maybe you need to check your Power Plan settings. Disabling Wake Timer is very useful. Many programmes, including Microsoft, will use some methods to wake your PC up. If you want to control the PC by yourself, just disable Wake Timer.