Quick question...

A friend of mine at playgroup has twins, a boy and a girl - apparently exclusively breastfed, though I think there is some comp formula feeding in there too - that are sleeping 12 hours without waking for a change or feed through the night. They're 3 months old and good size/weight. None of mine have done this ever, so I thought I'd check if that sounds normal? My 4 month old still clusters at night, anywhere up to as little as an hour between feeds which you know....is fine and great and I know he's healthy, but I get tired