Why is Windows constantly rebooting?

Question

Windows

Hello!
When idle, windows restarts by itself without warning,
what could be the problem?
and how to fix the problem

ps (wwindows 10-64x) It is on ssd
laptop model lenovo G571

Answer 1

It does not reboot, but falls asleep and, when active or turned on, loads into the state in which it was - this is called hibernation, sleep there or whatever.
If, for example, updates were installed during downtime, then after exiting from hibernation, it is the PC that needs to be restarted to apply them, because exiting from hibernation is not a reboot.