Although sleep disturbance is a prominent feature of mania, its polysomnographic (PSG) features have received little study. To investigate more systematically the PSG characteristics of sleep in mania, all-night PSG evaluations were performed for two to four consecutive nights in 19 young manic patients (age range, 18 to 36 years), 19 age-matched patients with major depression, and 19 age-matched normal control subjects. Manic and depressed patients displayed nearly identical profiles of PSG abnormalities compared with normal control subjects, including disturbed sleep continuity, increased percentage of stage 1 sleep, shortened rapid eye movement latency, and increased rapid eye movement density. These results are similar to those reported in previous studies of major depression, and they are consistent with the possibility that the sleep disturbance in mania and major depression is caused by the same mechanism.

To investigate the specificity of the dexamethasone suppression test (DST) for the diagnosis of major depression in patients with diabetes mellitus, we administered 1 mg of dexamethasone to 30 nondepressed diabetics and to 58 normal controls at 11 PM. Diabetic subjects received hemoglobin A1 (Hb A1) determinations, the Hamilton Rating Scale for Depression (HRSD), and five to eight blood glucose determinations during the 48 hours surrounding the DST. Results demonstrated a significantly higher rate of nonsuppression (plasma cortisol level, greater than or equal to 5 micrograms/dL) at 4 PM the following day among diabetics (43%) than among controls (7%) but no difference between these groups in the rate of nonsuppression at 8 AM. Plasma cortisol level at 4 PM correlated with Hb A1 level but not with duration of illness, HRSD score, mean blood glucose level, or maximum blood glucose excursion. These results suggest that the results of the DST used as a diagnostic test for major depression must be interpreted with caution in patients with diabetes.