The best sleep environment for babies is definitely a disputed topic. Some believe that a baby belongs in a sling all day and in the bed at their side at night while others believe that babies should have their own space for sleeping (crib or bassinet) away from the craziness of every day activities. What you choose to do is up to you, but since this blog is about how to get your baby to sleep the best possible, I'm going to focus on having your baby sleep in his crib or bassinet from the time he he born. I just don't believe it is practical for most moms to hold their child all day long (especially when she has other children) and sleep by his side all night (especially if the child is going to bed at an early, healthy time and there is more than one child). If we had nothing else to do but hold our child our day then things would be different. But that is not the case for most of us. There's cooking and cleaning and taking care of our other children--the list goes on. We have to find "a balance between instinct and practicality" and let baby "get used to sleeping in his bed". (The No Cry Sleep Solution, p. 71) I'm not saying that you can't ever hold your baby when he sleeps or have him sleep in their car seat while you are out and about, but I think the key is consistency and that means having him sleep in his bed most of the time.
In fact, I think it is probably a good idea to have your baby sleep somewhere else besides his crib on occasion. Read more about this in the post Varying the Sleep Location.
Be aware that babies under 3-4 months of age (sometimes only under 6 weeks) are not usually disturbed by their environment during sleep (Healthy Sleep Habits, Happy Child). This changes quite a bit as they begin to be more interested in their environment so watch out!
Related Posts:
Getting the Right Temperature
Light And Dark And Their Effects on Sleep
Sleep Attire
Sound And Its Effect On Sleep