Jackson and middle-of-night wakeups

Jackson woke up again in last night. There's this weird experience where he's up but doesn't seem awake. He'll call out (sometimes a cry, sometimes more of a yell) for Mommy and/or Daddy, but as soon as I come into his room, he gets mad ("I want MOMMY!"), and he won't explain what the problem is.  Sometimes he'll start yelling or crying.  Eventually he "wakes up" and almost instantly calms down, and goes right back to bed. But it takes a couple of minutes. 

 

Last night was particularly bad; he wouldn't "wake up" and when i tried to take him into the bathroom (sometimes the act of walking into the bathroom helps wake him up) he got more upset and started crying loudly. Finally, he made clear that his pillow had fallen on the floor! At this point he woke up, we got him his pillow, and he was back asleep...  not fun, though.