In her book, The Science of Parenting, Margot Sunderland taps the latest neurology research to tackle common dilemmas like clinginess, tantrums, and discipline. In the section on Separation Anxiety, Sunderland reveals that letting babies cry alone in the crib – practiced by parents who train their kids to sleep on schedule- causes “prolonged distress,” which floods her brain with high levels of toxic stress hormones. Eventually, she becomes hardwired for stress, leading to a nervous disposition she’ll have her whole life.
According to Sunderland, short bursts of crying are safe, but letting the baby cry on and on, until she falls asleep from exhaustion, is dangerous. “Babies can’t manipulate parents. Manipulation needs clear thought, and the brain chemical glutamate to be active in the frontal lobe. That doesn’t develop until toddler-hood, so she isn’t physically capable of controlling you.”