CITALOPRAM - DIFFERENTIAL SLEEP WAKE AND EEG POWER SPECTRUM EFFECTS AFTER SINGLE-DOSE AND CHRONIC ADMINISTRATION/

The sleep/wake effects of the selective serotonin re-uptake inhibitor citalopram were studied in both a single-dose study with three dose le vels (0.5, 2.0 and 5.0 mg/kg), and a 5-week chronic administration stu dy (15 mg/kg/24 h). Single doses of citalopram resulted in a dose-depe ndent inhibition of rapid eye movement (REM) sleep. After chronic cita lopram treatment there was a sustained REM sleep inhibition. Single do ses of citalopram resulted in only minor changes in non-REM (NREM) sle ep as well as in NREM EEG power spectral density. Chronic administrati on resulted in a major shift from SWS-2 to SWS-1. The observed corresp onding changes in EEG power density were regional. A 30 to 40 percent reduction of power density in the 0.5-15 Hz range in the fronto-pariet al EEG derivation was seen for the whole 8-h registration period. In t he fronto-frontal EEG derivation only minor changes were seen. A decre asing trend in NREM sleep power density between 0.5 and 7 Hz, usually seen during the course of the light period, was not observed in the ch ronic condition, but was seen in control and single-dose condition, su ggesting altered diurnal distribution of slow wave activity in the chr onic condition. The data indicate that acute and chronic administratio n of citalopram shows clear differences in sleep effect, which may be caused by alteration of serotonergic transmission, and may be related to the antidepressant effect