This is in a similar way to the adolescent brain reorganising itself during puberty.So far from breaking down, mothers' brains appear to be purposefully remodelling.If the brain is undergoing such substantial structural change, you might expect problems to show up when we test how new mothers actually think — but mostly, we don't see such problems.The largest study of its kind, published recently by Australian and US scientists, measured memory, thinking and processing speed in 150 new mums and 150 new dads But the evidence leads us away from pronounced shifts in brain function and towards the circumstances of new parenthood.The most obvious culprit is sleep