All-night spectral power and coherence analysis of six channels of EEG data from 6 healthy volunteers was performed. Integrated power and integrated coherence for the frequency bands of 0.1-7 and 7-12 Hz in 20 s epochs was plotted over the entire nights. Power and coherence increased with deepening slow wave sleep. With the onset of REM periods, power expectedly decreased, whereas coherence showed a further increase or maintained levels. With post-REM phase awakenings, power showed further reductions, and coherence decreased. The REM coherence results were most pronounced in interhemispheric right to left parietal comparisons (recorded vs. a Cz reference) in the 0.1-7 Hz band. It is hypothesized that the high interhemispheric coherence facilitates or reflects right-left transfer of information.