How to access the suspend button in Ubuntu 18.04 (Gnome Shell)

New Ubuntu 18.04 users may notice the lack of the “Pause” button in the Gnome Shell user menu. This menu has only 3 options: “Settings”, “Lock screen” and “Power off”:

After being idle for a period of time, the computer can automatically suspend (you can Settings > Power), but what if you want to suspend your computer as needed? There is no need to continue looking for the “hang” button, because the button cannot be found even in the user menu, even if it is there.

The solution is very simple, although not intuitive: open the user menu (the menu on the Gnome Shell bar at the top, which contains the power off button, etc.), press and hold Alt Key and then power off button should be changed to suspend button. Now you can click the Suspend button to suspend your Gnome desktop.
This is a gif showing that the power off button becomes a suspend button when held down Alt On Ubuntu 18.04:

Suspend power off button gnome shell ubuntu 18.04
Note that the button in the lower right corner toggles between “suspend” and “power off” (hold down the Alt key while recording this Gif). Yes, it’s easy, but…not discoverable.

You can also long press the “Power Off” button, it will change to a “Suspend” button. If you want to find a permanently visible hang button in the Gnome Shell user menu (no need to hold down the Alt key), -Pause button extension:Gnome shell user menu with permanently visible pause button

The Suspend Button extension only adds a Suspend button to the Gnome Shell user menu between the “lock screen” and “power off” buttons:
Install Suspend Button extension for Gnome Shell from the following location Gnomish expansion library.