7 month old not sleeping through the night!!!?

Arg, there's nothing worse than not getting enough sleep. I have two kids that are 18 months apart and share a pocketdoor between their rooms. So at night I keep our a/c fan in the 'on' mode to provide some white noise if one fusses during the night - you can also buy a white noise machine for your 23 month old, because inevitably there will be some noise (crying) that your 23 month old will need to sleep through. I also have an aquarium that plays music in both kids beds/cribs which seems to keep them entertained if they wake up in the night and helps soothe them back to sleep. Is there any chance your 7 month old is teething? Lying down can cause the area around incoming teeth to throb so a little tylenol or motrin might help? Good luck, hope it gets better.