The procedure for making a Windows device sleep is different for a desktop, laptop and tablet. To make a desktop, laptop or tablet sleep one has to search "Power options" in the search box.
To make a desktop or tablet sleep, tap or click "Choose what the power button does" under "Power options," then select "Sleep" and save changes. After it, press the power button to make the desktop or tablet go to sleep mode. To make a laptop sleep, tap or click "Choose what closing the lid does" under "Power options," then select "Sleep" and save the settings. After changing the power option close the lid to make the laptop go into sleep mode.