I have a Dell XPS 13 laptop which I have configured to sleep when the lid is closed. This normally works, however it appears sometimes it hibernates. At least, I think it hibernates, because it goes through the boot procedure. On the other hand, when I wake it from sleep the lock screen immediately appears.
I think this happens when I left the laptop sleeping for a longer period (10+ hours). Battery is nearly full.
Could someone shed some light on what could be happening here?