The "cry it out" / Ferber method taught our kids how to fall asleep on their own and saved our sanity. It used to take hours to get a baby settled and one of us had to be there the whole time. By letting them cry for a bit (occasionally showing up to reassure that we're still there), it took like a few days for them to go to sleep on their own. It was an amazing change, and one I wish I had put in place much sooner.

The idea (from what I remember, it's been years), is to put them down and leave the room. Then come back for a bit, and then leave for a longer period of time, say double, etc. It's gradual and, in our case, was ridiculously effective. Nothing works for everyone when it comes to kids, but it's totally worth trying after they pass, say, 6 months.

Once they get this down, it is important _not_ to walk on eggshells while the babies (and when they're older) are sleeping. Get them used to being able to sleep when there's noise. It'll make your life so much easier in the future, and you'll be able to bring kids into social situations, or bring social situations into your home, without the stress of kids unable to sleep due to noise.

Final word of advice - you will be showered with metrics and progress reports, statistics on how your child compares to others, etc. Ignore all that. Kids normalize over time and these deviations become way less significant. You'll have to make a conscious effort to ignore this noise, because fears for your kid are natural and will inevitably bubble up to the surface. Be the best parent you can be, and ignore the mountains of contradictory advice you'll get from friends, relatives, media and strangers on the internet ;) a lot of it is bullshit, so don't sweat it, your kid will be fine!