I found that a SNOO was very effective in the first 6 months. It is expensive, but it was way better than being even more sleep deprived. It plays white noise and rocks the baby if it senses them stirring. https://www.happiestbaby.com/
For those who intend to have one child only, they now have a rental program where they ship you the SNOO, you use it up to 6 months, and ship it back. Works out to about the same as what you'd lose by buying it new and reselling it at the end. Highly recommended!
