The authors studied the relationship of plasma cortisol secretion and
REM period latency in 25 patients with endogenous depression. The 8
patients (32%) with cortisol hypersecretion had a significantly shortened
REM period latency in comparison with the 17 with normal cortisol
secretion. Furthermore, an extremely short REM latency (20 minutes or less)
occurred almost exclusively in those with cortisol hypersecretion. The
authors discuss possible neurotransmitter disturbances responsible for
these abnormalities and the clinical implications of these findings.