My older two have slept in the same room for a few years now. I think DD was about 3 and DS1 was almost 2 when we moved here, which was when they went into the same room together. Tehy will stay in the same room together until we move, DD will be 7 by then and DS1 will be5 1/2. We did it this way so that the baby didn't wake them through the night, and they keep each other company of a night. Tehy very rarely wake each other up, even when they call out for us or have dreams ect. It's worked well for us so far and DD is 5 and DS1 is 3 1/2 now.