I remember long ago as a new parent thinking a baby was suppose to sleep in a crib, maybe a bassinet by your bed for the first few weeks but then a crib for sure. And for some children that's the right fit, but for our firstborn the crib seemed to be a baby prison. He would not sleep unless he was touching one of us in some way, ideally in our arms, on our chest, or attached to my breast! I was exhausted because I was so busy trying to parent the "right" way and I was feeling guilty if I let him sleep with us, so I was forcing myself to try and train our baby to sleep somewhere else. Then my sister gave me a book by Dr. William & Martha Sears, a pediatrician and RN couple. In it they mentioned a very unofficial study they had conducted on sleep patterns in infants & mothers, sleeping apart vs. sleeping together. In both situations the mother was responding to any cues that the baby needed care (this was not a cry-it-out situation) but the difference between the baby sleeping in the room by mom vs. out of the room was startling. And validating, for me! The study monitored the two month old baby's heart rate, breathing, and oxygen saturation levels and a pediatric pulmonologist studied the results not knowing which situation was with or without the mom nearby.
They found that when sleeping with mom (in the same bed) that the baby's breathing and heart rate were both more regular and the baby had NO dips in oxygen saturation levels. On the night the baby and mom slept apart, besides the irregularities with heart rate and breathing the baby had 132 dips in her oxygen levels. ONE HUNDRED AND THIRTY TWO DIPS. This study was specifically looking at oxygen levels and SIDS risks so that's pretty dramatic in my opinion! SIDS guidelines are ever evolving, I heard last year about their suggestion to keep a fan going in the baby's room for air circulation and that if the baby is sucking on a pacifier at night the SIDS risk was lower. I'm guessing the stimulation of the pacifier keeps them responsive? Though I believe a nipple from nursing accomplishes the same thing. 🙂 But do read the guidelines yourself and determine what is right for your family.
As a new parent, I really appreciated having that scientific evidence (however small the sample size!) to verify what I was intuitively sensing - that my baby slept better near me. My next child thoroughly confused us when she slept better away from us after the first couple months, preferring her own space. Then our third child arrived prematurely and came home on oxygen and monitors (so we literally could assess his heart rate and oxygen saturation levels at every moment of the day and night!) and you can bet that child was sleeping with us.
Every child will have different opinions but ultimately what I learned is that whatever you feel is best for your child is probably exactly what is best for your child! Don't let yourself feel guilty because of messages you may be getting from other parents, your own parents, the media, advertisers, your pediatrician, or any parenting book you read. YOU will know your child best, and you need to create the sleeping environment that helps your family sleep best. That may be something different for each of your children, too! For us we realized that I sleep best if my baby sleeps well, and if that means my baby is snuggled in bed between us and happily nursing all night long then I will be better rested, too. I personally find it FAR easier to nurse in bed with both of us dozing vs. getting up to retrieve a baby and having to fully wake up to return them to their own bed. Your mileage may vary!
(Thoughts from the Sears' Attachment Parenting Book, though also referenced in other of their works. I've loved every book I've read of theirs!)