It suggests that when your bundle reaches about 18 months, they begin to wake up more frequently, even if they aren't hungry, which is more common if they've been breastfed.
The researcher behind the study believes that babies wake their mum to prolong her "lactational amenorrhea", the temporary postnatal infertility that happens when you're not menstruating and still breastfeeding, to delay the birth of siblings.
On the findings, Professor David Haig said, "Short delays until the birth of a younger sibling are associated with increased mortality of infants and toddlers, especially in environments of resource scarcity and rampant infectious disease."
And it all stems from natural selection:
"Natural selection will have preserved suckling and sleeping behaviours of infants that suppress ovarian function in the mothers because infants have benefited from delay of the next birth."
But all we actually want is a good night's kip...
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