For the overall sleep spindle density (Figure 2), main effect of spindle type and nucleus was not significant (nucleus:F1,9 = 3.432, p = 0.097 spindle type:F1,9 = 3.490, p = 0.095), but there was a significant interaction between these factors (F1,9 = 6.203, p = 0.034). Post-hoc test revealed that the interaction was caused by the significantly lower fast spindle density in the MD compared to the ANT (p = 0.039). Main effect of spindle type was significant for the duration of sleep spindles (F1,9 = 5.756, p = 0.040) due to the longer slow sleep spindles compared to fast sleep spindles. Main effect of nucleus was not significant (F1,9 = 0.126,p = 0.730) and no interaction occurred between these factors (F1,9 = 2.621, p = 0.140) on the duration of sleep spindles.