They might wake you up every couple of hours for a feed but all for a good reason.
Researchers at Harvard University looking into breastfeeding and sleeping practices argue that by waking up their Mums for a feed they are delaying the return of her ovulation cycle (as well as reducing the time and energy to have sex).
This helps prevent the birth of a sibling with whom they would have to compete for food.
This can be a substantial benefit when food is scarce. In Somalia for example the mortality rate for 1 year-old children was increased fourfold if they had a younger sibling.
Professor David Haig, writing in the journal Evolution, Medicine and Public Health, says “there is no perfect harmony between mother and child. What is best for one is not necessarily best for the other”.
The research might explain why children can revert to waking up frequently in the night after 6 months and why babies fed formula milk tend to sleep more soundly (because there is a weaker incentive to demand food as formula is always available).