why does my Mac shut down, restart and reports sleep failure

To help troubleshoot your Mac, I would suggest that you consider using EtreCheck and posting the resultant report for us to review.

• You can download EtreCheck from here.
• Start EtreCheck from a normal user account. Optionally, you can run it from a user account with Administrator privileges.
• Select Options

  Verify that the two options: "Ignore expected failures in Apple tasks" and "Hide Apple tasks" are enabled." Note: They should be by default. You can skip this step the next time your run EtreCheck.

• Select a problem from the drop-down menu to enable the "Start EtreCheck" button. Optionally, you can add comments on what issues your Mac is experiencing, especially to aide others with similar Mac issues.
• Click on Start EtreCheck
• Allow the program to run to completion.
• When done, you should get a results report.
• Select the "Share Report" icon.

  Select Copy Report

• Paste the report to your reply post.