Sleep Inertia 

The sensation of being half conscious or only partially awake usually occurring immediately after waking up. It is also accompanied by a desire to continue sleeping.

Jim awoke early one morning for work after a rather weak-ass sleep. The force of his sleep inertia was strong that morning. So strong in fact that Jim couldn't help himself but fall back to sleep, consequently missing his shift.

Sleep Inertia by Woody89 July 27, 2012

Sleep inertia 

A result of not having social commitments that you care about, leading to a lack of fomo which makes you revert to a human's natural state of sleeping for hours on end.

"I slept for 12 hours last night and I'm still tired?"
"Yup probably cause of sleep inertia."

Sleep inertia by Calkimchi September 6, 2015