my daughter is 9. While this isnt every night. 2 or 3 times a week its still exactly as you described.
She just HAS to be near other people to be totally comfortable. She doesnt sleep well due to excema (a lot better than it used to be) and then, while laying awake she cant go back to sleep feeling too alone in the dark. Shes not afraid of monsters or anything bad happening, she just hates the lonely quiet of night and HAS to come ruin our nights sleep too.
Sometimes her sister will come sleep on her trundle or she will come sleep on our floor.
She just started getting wise last week actually. Twice, she just came in and made up her little bed and fell asleep on the floor without waking us up. At least that way, we cant send her back to bed.
Its pretty sad and most the time i feel bad for her, other times its hard not to be frustrated
Hopefully, your daughter is able to grow out of it faster than mine.