Polysomnographic parameters in first-degree relatives of unipolar probands.

We present polysomnographic data for psychiatrically asymptomatic first-degree relatives of unipolar depressed probands. Relatives were classified by proband rapid eye movement (REM) latency (reduced/nonreduced) and by personal REM latency (reduced/nonreduced). Reduced REM latency relatives, whether defined by the proband or by their own REM latency, had polysomnographic alterations consistent with those found in depressed patients, although none of these relatives was depressed at assessment. Reduced REM latency relatives with a history of unipolar depression were compared to reduced REM latency relatives with no history of depression. Virtually no polysomnographic differences were found. Polysomnographic alterations may be stable antecedents of the onset of depression.