Putting your PC into sleep mode manually or automatically can have several advantages. Technically, it is a low power mode, and sleep, suspend or stand by are all referring to the same mode.
What happens in the background is that the last state of the system is stored in RAM before power gets cut to all devices and systems that are not necessary for this minimal mode of operation.
The state is resumed when you hit the wake button, or when the keyboard or mouse are moved.
Sometimes, the computer comes out of sleep mode without you doing anything. This can have several causes, and this guide discusses several of them.
The first thing you should do is try and determine the source or device that is waking up your PC. Windows ships with several tools that you can use for the purpose, and this part of the guide explains how you can use them to find out more about the source.
Note that while it may reveal information to you, it is not always the case. It can happen that the diagnostic programs return no sources at all, or only unknown sources.
Still, it is a good idea to start here as a hit will provide you with the information needed to prevent that the computer wakes up automatically while in sleep mode.
Command line diagnosis
First thing you may want to do is check whether devices are responsible for waking up the computer automatically. Do the following to find that out:
Windows Event Viewer diagnosis
While still on the command line, type eventvwr.msc to launch the Windows Event Viewer.
This is the part where we apply the fix, to prevent that sleep mode is left automatically. If you have discovered what is responsible for it on your system, skip all suggestions except for the one that matches your issue.
If you do not know the particular source, try them all to find out more about it. I suggest you try one solution, put your PC into sleep mode, and see if it recovers from that automatically. If it does, that was not the solution for your issue, and you should go to the next suggested fix and try that.
Fixing the mouse
The computer mouse may be responsible for bringing the PC out of sleep mode. You can find out if that is the case, and disable the feature, in the following way:
Alternatively, open the Device Manager from the desktop Control Panel, locate the Mice and other pointing devices listing here, and right-click on the devices listed under it to select properties there. Or, simply double-click on the device in question.
Here you get the power management options directly, without having to go through the lengthy process described above.
Fixing Wake Timers
If a wake timer is responsible for waking your PC, you may want to check out the application that is responsible for that to prevent it from waking up your PC.
If you do not want any wake timers to be used, it is possible to disable the feature completely.
Make sure you make the change for all available power profiles.
Fixing network cards
Network adapters may wake the PC as well. You can check how the installed adapters are configured by running the following commands:
Side tip: You may also want to check your BIOS configuration for "wake on ring" and "wake on LAN" settings if available, and disable those.
Scheduled Reboot Task
On Windows 10, you will find that a reboot task may wake the computer up to install updates for the system and will wake up the computer even if no updates are available at that time.
To disable the task, do the following:
This is not enough however as Microsoft will re-enable it again in the future. To avoid this, it is necessary to change the permissions of the task on the operating system level.
Some versions of Windows are configured to run automated maintenance tasks. While you may not want to disable those completely, it makes sense to set them to a time of day that works for you.
Command line Fu
Here is a list of useful commands that can help you find out more about your PC's sleep mode and wake up configuration:
Run the command powershell from the command line to activate it.
If you want to know more about the sleep and wake functionality, use the following resources as a starting point:
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