inconsistent sleep mode activation

There are times when sleep mode is not activated (control panel / power options / power saver / change plan settings / time out settings for "turn off display" or "put computer to sleep").

Recently I saw that a notification of Windows Update was raised and that stopped the computer from going to sleep. What other events can cause the computer to be delayed from this great power saving feature? I usually run about 110 watts on my desktop, but in sleep mode I only use 3.5 watts.

How can these interruptions to going to sleep be identified and quieted, so that "we" go to sleep consistently?

Thanks,

See this: Find out what program is interrupting Windows Sleep mode - CNET

Thanks a lot. That was the solution. Here are my steps and what I learned:

cmd> powercfg -requests
You do not have the permissions required to perform this action.

I am the only user on the system; I am an administrator.

Next solution:
Need to run the cmd program as administrator. Either open context menu on cmd program and select "run as administrator" or create a shortcut to cmd and modify its properties: On shortcut tab, advanced button, check "run as administrator".

Then I get this, if no processes are stopping my machine from sleeping:

C:\Windows\system32>powercfg -requests
DISPLAY:
None.

SYSTEM:
None.

AWAYMODE:
None.

C:\Windows\system32>