Sleep slow waves have been recently classified into functionally relevant slow and fast groups exhibiting different connectivity dynamics along their transition from down to up state. Slow waves classified as slow switchers (depolarizing slowly <1.2Hz), demonstrated an increasingly stronger global connectivity index on the EEG than the faster ones until the up state is reached. Furthermore, older subjects, which produces a greater ratio of slow slow waves than fast slow waves, tends to have more difficulties to disconnect during deep sleep than the younger ones. In this study, we proposed to use simultaneous MEG/EEG recordings of 24 healthy participants (12 young, 12 older) to detect these slow waves and localize their activity on the cortex level. The objective is to see if there is a similar dynamic occurring on the cortex than the scalp and assess if aging is disrupting it. As expected, our results showed that slower waves recruit neurons from a broader cortical surface than the faster ones. This is in agreement with previous studies showing that slower slow waves propagate further than faster waves and have more extended sensor-level connectivity.