Find out what is keeping your computer awake
The first thing you need to do is check to see what running task prevents your computer from going to sleep or wakes it up from sleep.
Open the Start menu and type cmd into the search box. Right-click the “Command Prompt” listing and select “Run as Administrator.”
Once the command prompt opens up for you, type the command powercfg -requests and press Enter. If any process is stopping your computer from going to sleep, it will be displayed here.
Above you can see clearly that Windows is currently installing updates, so this is preventing the sleep process, but sometimes the information displayed by the command is vague. Nonetheless, you will usually get enough information to direct you toward fixing the issue. Below are other areas you can explore to solve this problem on your Windows 10 PC.
Turn on “Allow Computer to Sleep” in Power Options
Select “Settings” from the Start menu, then click the “System” option.
Click “Power and Sleep” from the list of options. Make sure that the options under “Sleep” are set to a desired value.
Click “Additional Power Settings” under “Related Settings.” You will be redirected to the control panel.
Select “Change Plan settings” under your chosen power plan. Then click “Change advanced power settings” from the resulting screen.
On the “Power Options” window, expand each setting to make sure nothing is preventing your computer from going to sleep.
Once you are done, click “Apply” to save your settings.
This should fix the problem for you. However, if you are still having problems making your Windows 10 computer remain in sleep mode, there is another thing you can try.
Using Task Scheduler
Fire up the Start Menu and search for “Task Scheduler.” Click the correct entry from the results.
On the left tree, expand “Task Schedular Library -> Microsoft -> Windows -> UpdateOchestrator.”
Select the “Reboot” setting in the center, and disable it using the options on the right side of the screen.
Also double-click the other options on the list, and navigate to the “Conditions” tab on each. Make sure “Wake the computer to run this task” is unchecked on each setting.
Following the above steps should work for you, but it has been observed that sometimes the settings reverse after a system update, so it’s probably a good idea to keep an eye on it after each system update. Let us know if any of the possible solutions listed above work for you and if there’s anything else you’d like to add in the comments below.