4 year old waking every night

My 4 year old has recently started waking up every night. No reason really, no crying, no nightmares, no problems.. except getting up & coming into our room between midnight & 4am.
She has always been a good sleeper, gave up daytime naps at 18 months old, has plenty of exersize [kindy etc].
One issue we thought of is, she has a touch lamp in her room, and always has. We decided a few weeks ago [When the waking started happening..] to turn that off, and have a light on in the hall instead.

Any suggestions?

Cheers

My boy is similar.
He often wakes between 1 and 4am and will come and climb in with us. Sometimes this happens several times a night.
We've reached a stage where we're trying to get a bit firmer with him but it is a little tricky as I think he often does it on autopilot without being fully awake.
No real advice sorry, but you're not the only one!