Unsure what's going on here. You'll fall asleep sitting on your bed? You may have other issues to contend with besides this. Suggest you see a doc and describe this.
I had this happen before, I was once playing Destiny for the first time, fell asleep only to wake up and still feel like I was holding my ps4 controller. It's related to stress, the mind hadn't completely shut off to rest and so when you wake up, you still feel like you are doing the last thing you did before you fell asleep. Also when I first vmbecame a CNA after being completely exhausted from a 16 hour shift, come home and fall asleep waking up a couple hours later feeling like I had feel asleep on the job and needed to go back to work. If you've been under a lot of stress as of late, you need to regard how it has been affecting you and take a break to catch up on your sleep also lay off of the energy drinks or caffeine in general which has shown to be the lead cause to sleeping disorders and affects to the mind and body. It wouldn't hurt to look into a sleep study where a Doctor will set up a day where you'll go in to be observed while you sleep, and monitor your brain waves and figure out what is causing the symptoms.