Effect of slow-wave sleep deprivation on topographical distribution of spindles

Spindle activity, visually scored in the 12-15 Hz range over antero-posterior midline derivations, has been assessed in ten normal subjects during a baseline and a recovery sleep after 2 nights of selective slow-wave sleep (SWS) deprivation. The recovery sleep, characterized by a significant increase of stage 4 and SWS as compared to the baseline, revealed that sleep spindles are reduced in the first NREM sleep cycle. The size of this reduction in spindle density progressively decreased in the course of the night, paralleling the depletion of SWS rebound. Topographical distribution of spindle activity showed a global linear increase over consecutive NREM-REM sleep cycles, regarding to the whole antero-posterior midline EEG derivations except the occipital one. It is concluded that the SWS rebound after 2 nights of selective SWS deprivation is associated with a reduction of spindles during stage 2.