Recent evidence indicate that humans can learn entirely new information during 3 sleep. To elucidate the neural dynamics underlying sleep-learning we investigated 4 brain activity during auditory-olfactory discriminatory associative learning in human 5 sleep. We found that learning-related delta and sigma neural changes are involved in 6 early acquisition stages, when new associations are being formed. In contrast, 7 learning-related theta activity emerged in later stages of the learning process, after 8 tone-odour associations were already established. These findings suggest that 9 learning new associations during sleep is signalled by a dynamic interplay between 10 slow-waves, sigma and theta activity