Sleep is definitely a huge issue when they're very small. I would recommend looking into sleep training and some version of letting them learn to self-sooth (aka "cry it out"). It's not for everyone and it can be emotionally difficult on the parents, but typically within just 3 days you can get your kid sleeping through the night and it sticks ~forever. Do a little reading on the topic, and make sure you're prepared to sit through the crying without intervening and your kid is old enough. We did this with both our kids around 6 months and they have slept soundly through the night ever since (oldest is now almost 4). Biggest life upgrade of our parenting experience.
