Is it true that formula fed babies sleep longer than breastfed babies?

It is unlikely that formula fed babies sleep longer than breastfed babies. This thinking probably came about because formula fed babies usually need fewer feedings in the day since formula takes a longer time to digest (formula contains more casein which takes longer to be digested, while breast milk has more whey that is easier to digest). However, like what Diana mentioned, night waking is not solely due to hunger. Therefore, a baby is still likely to wake up (especially at the end of each sleep cycle) at night regardless which type of milk he/she was given. If you have no intention of weaning your baby (and is only considering formula because of your baby’s night waking), it is probably best to continue with breastfeeding. It will minimize nipple confusion and also help keep your supply stable (one of my friends started having both formula and breast milk feedings and observed a drop in her supply).