Effects of low-dose dexamethasone on sleep EEG patterns, plasma cortisol, and the TSH response to TRH in major depression.

Dexamethasone (DEX) (0.5 mg, P.O.) and placebo were administered at 2300 h in randomized design to 19 patients with major depression and the effects on the sleep electroencephalogram (EEG) were studied. In addition, the thyroid stimulating hormone (TSH) response to thyrotropin releasing hormone (TRH) and basal plasma cortisol concentrations were assessed the following morning. DEX did not affect sleep architecture or continuity variables, including rapid eye movement (REM) latency, REM activity and REM density. Similarly, DEX did not significantly influence the TSH response to TRH (delta max TSH). In contrast, plasma cortisol concentrations were significantly suppressed by DEX. The results indicate that, as opposed to higher dosages of glucocorticoids, 0.5 mg DEX had minimal effects on the sleep EEG or delta max TSH in depressed patients.