Custom sleep function for Nextion
I solved the problem using a Nextion timer. (tm0)

I got a timer and change tim value. ( unfortunately Nexion allow to maximum to 65535mS). vscope should be globle, otherwise you cant use timer in every page.

I reset the timer in page touch event. In timer event I put this code.

if(tm0.tim==60000) //reset time in mS
{
   page 0 //specific page to load
}