(a) Following a screening night and a regular sleep-wake schedule for 1 week, the participants (N=100; 59.4±5.3 years; 68 women) slept in the lab at their habitual times under electroencephalography (EEG) recording. We extracted the density and coupling of spindles and fast and slow switcher SWs over frontal derivations during N2 and N3 sleep stage from EEG recordings. (b) PET signal uptake was measured over the medial prefrontal cortex (MPFC) depicted in yellow. (c) Significant negative association between the MPFC Aβ burden and spindle-slow switcher SW coupling. (d) No association between the MPFC Aβ burden and spindle-fast switcher SW coupling. (e) Analysis of the anchoring of the spindles onto the SWs yielded a difference in preferential coupling phase of slow (red) and fast switcher SWs (light blue) (the y axis represents the number of spindles starting at a specific SW phase). (f) No association between the MPFC Aβ burden and slow switcher SW density. (g) No association between the MPFC Aβ burden and spindle density. (h) No association between the MPFC Aβ burden and the ratio between .5-to-1 Hz over 1-to-4 Hz overnight cumulated EEG power. Except for *, p-values and r²β* were computed from generalised linear mixed models (GLMMs) referred to in the text. Simple regressions were used only for a visual display and do not substitute the GLMM outputs. *Post-hoc test p-value is reported while Aβ burden-by-SW type interaction yielded p=0.009; r²β*=0.07 (see text). We used the cosine value of the phase of coupling in the GLMMs (see Materials and Methods).