Is screaming in the middle of the night an anti-sibling baby plot?

Scientists speculate that babies may have evolved to wake up in the middle of the night because overnight breastfeeding delays ovulation and, thus, the creation of a new sibling to compete for resources. (Word of caution: This idea might be hampered by a focus on Western babies. I recently read a book that suggests Western idea of "normal" nighttime waking aren't the norm everywhere.)

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