Dysphoric milk ejection reflex to nipple/areolar stimulation, thoughts of the baby or of breastfeeding, or overfull breasts, travels through both brain and bloodstream, causing emotional changes in the brain and the release of milk in the breast. Prolactin, released in a gradual wave that peaks after the beginning of a feeding, is responsible for continued milk production. Dopamine inhibits the release of prolactin, so dopamine levels must drop in order for prolactin levels to rise. Some speculate that the necessary dopamine drop is similar to (and timed with) the oxytocin spike – a sort of negative image – but that in D-MER mothers it
Period (gene) nucleus as well as areas outside the SCN. Additionally, while Drosophila PER moves between the cytoplasm and the nucleus, mammalian PER is more compartmentalized: mPer1 primarily localizes to the nucleus and mPer2 to the cytoplasm. Familial advanced sleep-phase syndrome known to be associated with mutations in the mammalian Per2 gene. People suffering from the disorder have a shorter period and advanced phase where they go to sleep in the early evening (around 7pm) and wake up before sunrise (around 4am). In 2006, a lab in Germany identified particular phosphorylated residues of PER2 that are mutated in people suffering of FASPS.