Paroxetine is a selective and potent serotonin reuptake inhibitor with reported antidepressant properties. Since changes in the regular sleeping pattern were described as side effects under treatment with paroxetine, the impact of the drug on the sleep architecture is of major interest. The present study addressed the question of subchronic effects of paroxetine medication (30 mg/day) in eight healthy male volunteers in a double blind, placebo-controlled crossover-design. Conventional sleep EEG parameters and additionally computed spectral power analysis based on FFT of 20-s time epochs in the delta, theta, alpha, beta and gamma frequency range for different sleep stages after 4 weeks of treatment were investigated. Subchronic paroxetine administration in healthy subjects led to a prolonged REM latency and a decrease in the number of REM phases, whereas sleep efficiency, total sleep time, sleep onset latency, number of awakenings, and awake during sleep period time were not altered by paroxetine medication. Moreover, we could not detect any alterations of the spectral power values in certain frequency bands during NREM or REM sleep following subchronic paroxetine medication.