Ambulatory polysomnography of never-depressed borderline subjects: a high-risk approach to rapid eye movement latency.

The sleep parameters of never-depressed borderline subjects and age- and sex-matched normal controls were compared by continuous 48-hr ambulatory electroencephalographic (EEG) monitoring. Borderline subjects had a significantly shorter rapid eye movement latency, normal architecture of rapid eye movements sleep, and had familial risks for mood disorders four times greater than in the families of controls. Reduced latency of rapid eye movement can be a trait indicator of liability to depression, present before the clinical appearance of the disorder, and demonstrable in a putative high-risk population.