Aeon: Was Freud right about dreams all along?

Prolactin, which enables mothers to produce milk and stimulates the testicles, rises rapidly as sleep sets in and peaks between 3am to 5am, when REM predominates. Release of prolactin can be blocked by sleep deprivation. Similarly, oxytocin, which is linked to bonding during sex, and testosterone, which is tied to the sex drive, both peak at about 4am, when REM rules.

via Was Freud right about dreams all along? – Patrick McNamara – Aeon.