I am a BIG fan of sleep sacks and swaddles. From day one, Charlotte was either swaddled in a blanket, or one of the swaddles above. She really slept great, and it kept her from scratching herself, and waking herself up with arms flailing.
Since you put babies on their backs to sleep, swaddles are great. Around 3 or 4 months, Charlotte starting flipping to her stomach. We decided to stop swaddling her, since they need their arms free. She is a bona fide stomach sleeper now. We decided to transition to sleep sacks as opposed to putting her down in footed pjs. Since you can't use loose blankets, sleep sacks are great.
Charlotte's night time wear consists of a long sleeved, white onesie, and a sleep sack. I think it seems cozier, and more like sleeping under a blanket. So here are the contenders. I added the swaddles, even though we are out of them.
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Aden & Anais Swaddle Blankets - This is a great line of products. All items are made with a super soft and breathable muslin fabric. You can find Aden & Anais are various places, and now in Griffin at my new baby booth! These blankets also make great stroller blankets. I always have one nearby.
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Miracle Blanket - This is a great option for babies that bust out of traditional swaddles. It really keeps their arms in.
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Summer Infant Swaddleme - Another option, that is super easy. Has velcro, and you can change diapers without taking the entire thing off. We used these a lot.
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Halo Swaddle Sleep Sack - These are a sleep sack, and swaddle in one. Charlotte liked these too. You can take the swaddle piece off, and just use as a sack too.
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Halo Sleepsack - This is a basic sleep sack. I like the thinner cotton ones. I never did the fleece, because I worried she would get too hot. We try to keep the room cool at night.
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Aden & Anais Sleeping Bag - My all time favorite sack because they are super long. If you have a tall baby, you will find they outgrow sleep sacks fast. Charlotte is in a small, and is just now starting to fill it up. The small is up to 6 months, and she is a tall 8 month old. These are a single layer of muslin, and very breathable. They have been great during the summer.
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Aden & Anais Cozy Sleeping Bag - Same as above, but this one is four layers of the soft muslin. We have a medium, and will probably start using it now since it's chilly out!
As I mentioned, I am now selling the Aden & Anais brand. I can order sleep sacks, and they come in a great variety of colors and patterns. I am doing a "baby booth" with a friend at Gigi's Antique Griffin. It's in the works, and I will be posting pics soon.