Night Terrors?

Here lately, my perfect sleeper (Tyler) has been getting up from his bed after we put him in it.  It doesn't matter if its for nap time or bedtime.  It started about a week and a half ago and just involved him getting up out of his bed and opening his door, then going back into his bed.  Then that led to him getting up and opening Megan's door and getting in to her crib with her.  AHHH!  Dealing with one kid that won't sleep is enough.  I certainly didn't want him getting in Megan's room and waking her up all the time!  Yet, other than turning his doorknob around so that he couldn't get out (locking him in is probably child abuse, I know), I didn't have any ideas as to what to do to keep him out of Megan's room.  I came home from work one night to see Tim had thought of this idea.

A gate over Megan's doorknob.  Ingenious! :)  It certainly kept him out but definitely didn't keep him from getting out of his bed and not sleeping.  Since then, Tyler has started showing us that it seems to be more of a just-want-to-get-out-of-bed-and-play thing.  He has been terrified of the door being closed or a night light not being on.  He has never had a night light before and has never had any fear of the dark. He says "Mommy, I need you in my bed" and whimpers as he says "Mommy, please don't close the door."  It devastates me to think that something scars my little boy! :(  Last night, I got home from work to hear him crying in his room and I went in to see him cowering by his night light.  I laid him back down and asked him what was wrong and he said he was scared.  I asked him of what and he said "the spiders are going to get me!"  I have no idea where he would have gotten this idea.  I prayed with him and reminded him that Jesus would keep him safe and that Mommy and Daddy were just down the hall. He seemed so exhausted that he just about fell asleep while I was stroking his cheek.  I turned on an additional little lamp, closed his door and went back to my room.  About 30 minutes later, he woke up screaming like someone had hurt him.  Of course, I sprinted down the hall and he pretty much met me at his door.  I scooped him up and he grabbed my neck so hard. :_(  I just don't know what more to do for him.  Are these night terrors?  Could their be demonic activity surrounding my sweet boy? Praying and praying and praying, thats for sure.  It just breaks my heart to see him so scared.  Adding to it, I am afraid that since he is now getting up that he might get into something in the middle of the night.  So, needless to say, very little sleep has been had for me over the past couple weeks.  I tell you what though...it certainly has made me spend more time in prayer!