M.P.
The very best thing for a restless night is exercise. Get a half hour fast walk in or follow an exercise video. An 18 month old is very tiring, but that is not sufficient exercise. If you are feeling the springs of your mattress or hearing them creak when you are trying to sleep, you might want to try a mattress topper unless you can afford to just get a new mattress. I've been through the restless nights for the same reasons and these do help.