DS is 13mo and has a sleep sheep. We started using it when he was quite young (about 3mo) and just pop it on now when he's going to sleep more out of habit I think. I think it's good right now as its a familiar sound and it actually blocks out quite a bit of noise eg passing traffic, sirens, noise from upstairs neighbours. It doesn't totally get rid if it but does muffle the noise a bit which helps when dS often looks for reasons to stay up and alert! You can slip the little sound machine bit out of the sheep toy and take it with you when travelling. We've done this and it helps add some familiarity to the situation when you're moving around and using travel cots etc.