The light from these devices can suppress melatonin (our body's natural sleepy hormone). (sleepinglittledreamers.com)
Babies release sleepy hormones just from sucking, whether or not their bellies get full, so pushing off a feeding by using a pacifier can cause baby to not eat often enough or get enough milk. (lactationlink.com)
It has much to do with the fact that the daylight hours are longer, thus interfering with the release of Melatonin (our «sleepy hormone»). (swanling.com)