Figure 3.

NREM sleep spectral activity in the C_z derivation, averaged by 2-h periods during baseline night (BL), first and second nights of sleep fragmentation (FR1 and FR2), and recovery night (REC), for morning types (M-types) and evening types (E-types). The 2-h periods are identified by their lower boundary value. A. Time course of SWA (1–5 Hz). The star indicates a significant between-group difference. B. Time course of theta activity (4–8 Hz). C. Time course of high sigma activity (14–16 Hz).