Hi Lilacgirl.
My daughter, also 10, always has to sleep with an enormous bear! She says she can't sleep without it. However when she went on a school trip for 3 nights, we couldn't fit this bear in the bag (its bigger than my 14month old son!!!!) so I told her she'd have to leave it behind. She worried a bit during the week before she went away, but had NO problems sleeping at all! She was so tired after all the activities, and so excited about being with all her friends, she slept really well. If you or your husband aren't too concerned about the sleeping pattern, I wouldn't stress over it. She'll give up when she's ready. If you are concerned, then gradual withdrawal and rewards for falling asleep on her own, are all I could recommend. After a week of managing it herself, you could reward her with an outing, or something she really wants (nothing expensive as it can get out of hand then!) Things like that work with my 10yr old. It's amazing what a reward sticker can achieve!!!