My daughter is 6 months old, and has been sleeping through the night since 5 months old. I have been tossing up whether I write this blog because we'll probably hit a sleep regression at some stage and all of this will be for nothing.
I just want to say that I am certainly not an expert and I am the first to admit that luck is about 95% of the puzzle - we have a good sleeper! BUT I have been asked by a lot of people how we "did it" and so I will share a few things that worked well for us. Spoiler alert, there's no magic bullet and I'm not going to say any of this will work for you.
Have a consistent approach between parents
When my husband went on paternity leave, he was now responsible for putting our daughter down for all her naps while I worked. A week or two in we noticed that there was an inconsistency. He would rock her to sleep or pat her to sleep. Whereas I was moving towards teaching her to self settle. I explained what I was doing, and we formed a consistent approach to putting her to sleep. This meant that she started to understand the routine before sleep and the cues that it was time for a nap.
Having an inconsistent approach to nap time (and bed time) will just confuse your baby and frustrate you both. Speak to your partner about the way you plan to teach your baby to self settle and make sure you're doing the same things.
We've had to get over this hurdle again with my mother-in-law looking after our daughter during the day while I work. She does the exact same things that we do at nap time, which has been really helpful in keeping things consistent.
Maintaining this consistent approach has taught our daughter to self settle beautifully. I'll see her wriggling around on the monitor during the night and she happily puts herself back to sleep, because she knows how to.
Have a set of solid sleep cues
I used to think it was a bit of a farce, having cues that it was time to sleep, but we've found that a few things really help. These are what works for us and our baby though, so experiment and find the things that your baby associates with sleep time.
Having a sleep sack: Since it started to cool down our daughter has been in her duvet weight Woolbabe sleep sack. We're going to have to get her a summer one for the warmer months I think because this thing is a powerful sleep association! It's brilliant because she knows when we pop her sleep sack on, it's time for a sleep.
White noise machine: We have an Gro Ollie the Owl sleep aid. It's great! We switch it on and it's a clear cue that it's nap/bed time. Even better, it drowns out noises that might wake her up.
Reassuring language and a speedy getaway: Now that she's six months old, we'll put her down in her cot with the above things done and say "Have a good sleep! See you in a little bit!" or something to that effect and then leave the room. 90% of the time she settles herself to sleep, but if she escalates to any kind of crying we go back in and give her a reassuring pat or cuddle.
Different sleep cues for bedtime: I hear you, it's great to know what works for naps but WHAT ABOUT BEDTIME?! Well, it's all pretty similar except with the addition of two songs from mummy at bedtime. I always sing the same songs, and it's become a really special time of the evening for us as I get smothered in kisses and cuddles.
A predictable evening routine
I've written before about my feelings about pre-set, one size fits all sleep schedules. I think you need to find your OWN rhythm, and a routine that works for your family. Our evening routine is always the same, even if we're away from home. Ours is just a variation of the four B's (bath, boob, book, bed) but it works well for us.
Bedtime is almost always the same (7pm) but sometimes it's earlier if she's really tired. So the whole routine starts at 6pm with a bath with mummy, then a feed and chats with us both on the couch, and then bedtime. I previously read that your pre-sleep routine should be pretty similar for naps and bedtime, but I've found that having a different routine for bedtime works well (bar the small things I mentioned above that happen at every sleep time).
Getting all the calories in during the day
Now this one is TOTALLY dependent on your baby, but for us we've found it works really well for me to breastfeed every 2 hours during the day. It can be tricky with me working all day, but I find since I started doing every 2 hours instead of every 3, we have zero night wakes. Amazing huh!? I can't comment on formula feeding because I don't use formula, but I'd imagine you could find a similar rhythm that keeps baby's tummy full during the night.
You can try different combinations of times between feeds to see if it helps at all. We've also introduced a small amount of solids now which makes evenings a little different, but she still takes a full feed before bed even if she had solids an hour or so before.
So that's it really! Like I said, I strongly believe that 95% of it has been pure dumb luck, but I hope that even one of these things helps someone else. And if your baby isn't sleeping through the night, that is TOTALLY OKAY. They'll do it in their own time, when they're ready to.