Figure 1.

The mean cerebral and muscular hemodynamic values during different sleep stages in all subjects. BV is blood volume. *Significant decline (or increment) in the mean hemodynamic values in sleep stage 1 (N1) and 2 (N2) compared to wakefulness (W) (P < 0.05). ⁺Significant decrement from N1 to N2. ^#Significant increment or decrement from N2 to SWS. The hemodynamic changes are expressed in arbitrary units (A.U.), as the mean value of first 30-sec measurements during wakefulness is set at 0.