crack-sleep
When you fall sleep, primarily out of being tired, way before getting ready to bed, and then you wake up in the middle of the night hating it as if you would have had already a full night's sleep. Most of the times you are even wearing your regular clothes and do not really remember how it happened.
I just woke up, and it's 3am! Wasn't I just laying down waiting for the water heater to get a cup of tea? I crack-sleep all the time!
sleep crack
When you get little to no sleep and thus are super hyper/weirdly energetic as a result as if you are on crack.
Person 1: HEYYYY I GO ZERO SLEEP LAST NIGHT YEET!
Person 2: Someone's on sleep crack
Person 2: Someone's on sleep crack