Sleeping Mac

[garry]

I have an iMac and am running OS High Sierra 10.13.2. When I click on sleep for the imac to rest for the night. it shuts down and restarts almost all of the time and takes away tabs and other things that I have on the screen in progress. Sometimes it renews them but other times I have to sign back in to the things and have lost places and tabs. What is causing the shut down after updating the last time with High Sierra

 

[MightyGem]

Does it sleep ok by itself?

 

[garry]

Does it sleep ok by itself?

It sleeps OK alone but that is not the problem. It shuts completely down and cries through the night then wakes later with a headache and missing information.