brain performance. sleep has many functions that s clear but what we re focusing on here is the role that sleep plays in memory for. a long time we thought that memories are formed during rem sleep but that s not correct. our research shows that memory is actually primarily formed during deep sleep. so people who sleep deeply are also sleeping healthily because on. different phases of sleep are recorded with electroencephalography or e.g. brain activity is typically charted at low amplitudes during rem sleep deep sleep phases on the other hand are characterized by very high amplitude slow brain waves called slow oscillations these waves play a decisive role in sleep quality. our