Figure 3. shows examples for fast sleep spindles from the same patient and nucleus, associated with and without ripples. Significant main effect of association was found for the spindle density (F1,9 = 53.180, p < 0.001,ηp2 = 0.855), due to the higher SP(pure) density compared to the SP(ripple) density. The main effect of spindle type and nucleus was not significant (spindle type:F1,9 = 3.489, p = 0.095,ηp2 = 0.279; nucleus:F1,9 = 3.432, p = 0.097,ηp2 = 0.276), but significant interaction occurred between these factors (F1,9 = 6.202,p = 0.034, ηp2 = 0.408). Post-hoc test revealed that the interaction was due to the significantly lower fast sleep spindle density in the MD compared to the ANT (p = 0.027). The duration of sleep spindles was affected by the ripple-association, as indicated by the significant main effect of association (F1,9 = 54.661, p < 0.001,ηp2 = 0.858), on average, ripple-associated spindles were 232 ms longer than pure spindles (Figure 4). The main effect of spindle type was also significant, as longer slow spindles were detected compared to the fast spindles (F1,9= 5.577, p = 0.0425, ηp2 = 0.383). The main effect of nucleus was not significant (F1,9= 0.404, p = 0.541, ηp2 = 0.043), and no interaction occurred between the factors (p > 0.137, at least).