Bad sleeper!

Meggie
My 15 month old son is a terrible sleeper! Rarely sleeps through, normally up for about 3 hours when he wakes in the night. He's an extremely light sleeper. I'm expecting baby no2 any day now and very worried that the newborn cries and wakenings will make my son even worse! Do you think a white noise machine would be a good idea?! If so, any recommendations? X