Why do contractions happen at night?
Hormones = More Contractions at Night
At night, the hormones that increase the contracting nature of your uterine muscle – estrogens and prostandins – predominate. And oxytocin and melatonin hit their peak at night too. Why do most contractions start at night? This fabulous hormone interacts with oxytocin to promote contractions, and melatonin is the hormone that is responsible for encouraging us to go to sleep! So clearly it reaches it's peak during the dark hours, making us more likely to go start contracting in the evening.