Dubbed "Insta-wakes", where the Mac was told to go to sleep, the screen goes dark and it suddenly comes back to life. As if to say "No, I don't want to sleep".
There appears to be a couple of potential causes.
First step is to try to identify the cause. Either click on the event in the Sleep History, or select "Overview", then "Insta-wake" (from the sidebar) and double click an entry in the list.
Once the event information is listed in the sidebar, look for "Woken By".
If insta-wakes continue, Please see Apple's guides on cleaning your Mac, to remove any dust or dirt that might be causing this.
We've not experienced problems ourselves, yet support forums have people with these issues, and potential solutions.
We DO NOT recommend updating the macOS, this often incurs new problems. If you're running macOS 10.x and see a 10.x.x update, this should yield the least disruption and hopefully solve the issue.