As Rebecca Maberly’s newborn baby latched on to her breast for a feed she was engulfed by a sudden wave of despair. “I felt suicidal, and so hostile towards my baby that I wanted to throw him across the room,” she recalls. It may sound like a symptom of post-natal depression, but Rebecca was suffering from a recently discovered physiological syndrome called Dysphoric Milk Ejection Reflex (D-MER). D-MER is thought to be caused by a sudden drop in the “feel-good” hormone dopamine, which pre-empts the release of breast milk. This leads to strong negative emotions and lasts for as long as milk let-down continues – usually between 30 to 90 seconds.