E has been leaking through his diaper lately (he's a tummy sleeper) straight through his sleeper, sleep sack and leaving a big wet spot on the sheet (only overnight). It doesn't dry by the time he's ready for a nap, so I've been changing the sheet because little dude is not cool sleeping in the wet spot (I mean, I don't blame him). I could just throw it in the dryer while he's awake but if I'm going to take if off I might as well put a clean one on.

I ordered extra inserts to put in his diaper overnight so I'm hoping that will stop the leaks, but then I won't have a reason to change the sheet every day. So how often should one normally change them?