The relationship between episodic variations of plasma prolactin and REM-non-REM cyclicity is an artifact.

The concept of concomitance between nadirs and peaks of plasma levels of PRL and, respectively, rapid eye movement (REM) and non-REM stages in sleep was reevaluated using 24 nighttime profiles of plasma PRL collected at 15-min intervals and the corresponding polygraphic recordings of sleep. The subjects were 5 healthy young male adults. Data were examined using the methodology described in the original report, consisting of averaging across individual nights PRL levels during REM and non-REM sleep stages as well as using a detailed spike by spike analysis of each individual pair of hormonal and sleep profiles. We showed that in our subjects, there was no relation, other than a purely random one, between episodic PRL fluctuations in plasma and REM-non-REM cycles.