Over the years there have been numerous innovations and fads that purport to help babies sleep. Some of these, like Houdini-proof swaddles and basic cotton sleep sacks, have become nursery staples that actually do improve sleep. On the other hand, other devices have fallen out of fashion due to limited benefits or have been recalled over significant safety concerns. The latest trend in baby sleep attire is weighted sleep sacks, but do they live up to the hype? The Science Wei