iMac Awakes from Sleep after Upgrading to Catalina

Since I upgraded to Catalina, I'm having issues with the SLEEP capability.

At night, when going to bed, I always set my Mac to SLEEP. In the past the unit would stay shut down until I came in, perhaps the next night, and hit a key to wake it up.

Since upgrading, I can put the unit to SLEEP, but it will automatically wake itself at some point, and it doesn't go into screen saver mode either, once awake. So I wake up in the morning and the screen is up on its normal screen with no saver running.

Has anyone else had this problem? What, if anything can be done?