I also discovered, that if I run the command: pmset -g, then it'll list services/daemons preventing sleep as well. There is a column in Activity Monitor called 'Preventing sleep': Last time it happened, it was 'Spotlight', that had 73% in that column. Even though that it can be one application draining the energy, while it's another one that prevents the Mac from sleeping.

I can try looking at that, after this happens, to see what drained the energy. In Activity Monitor, in the Energy-pane, there is a column called '12 hr Power'. I found this answer here: Disable Bluetooth or disconnect Bluetooth connections when lid is closed - but I'm just baffled that I need some third party application to achieve this? Solution attempt 3: Which applications spent energy over the past 12 hours

I tried Googling for, disallowing Bluetooth-connections while in sleep mode. Solution attempt 2: Disallow Bluetooth-connections while in sleep I tried going through the System Settings. I wonder, if the battery-consumption is because this watcher can run, while in sleep-mode? Hmm. I'm a web developer and run the npm run watch-command quite frequently. Watcher-programs (running in terminal).Sometimes I can put on my AirPods, and then they pair with my Macbook Pro, even though it's in my bag in sleep?! I'm not sure, what the real culprit-applications are, but my theory is: But every now and then, I take it up from by bag - and then it's steaming hot and have it using up a good portion of the battery. I love that I can simply close it, so it goes to sleep - and bring it with me.

Macbook dont sleep