Put mcu to sleep

I’m new on forum.
I want to know if what I want is achievable and how. I want Nextion display to send some data to mcu before display goes to sleep. Mcu will then act upon data arrived and go to "sleep "itself. I’m using thsp command to put Nextion to sleep.
Is there a way or workaround that makes Nextion do something just before no-touch-then-sleep timer expires?
Any thoughts and suggestions are greatly appreciated. Thank you.

The Nextion will send 0x86 0xFF 0xFF 0xFF before going to sleep.

Thank you Fjodor. I must have overlooked the section on returned data. I have noticed that Nextion editor does not send anything. I will try to compile and upload project to display. Maybe then, the display will send it.

I found another issue that is bothering me.
Even thou I don’t have system variable sendxy set to 1, Nextion still sends touch coordinates when asleep. Why and how to disable sending anything when display is sleeping?
Thanks in advance.