Overnight improvements in two REM sleep-sensitive tasks are associated with both REM and NREM sleep changes, sleep spindle features, and awakenings for dream recall.
Neurobiology of Learning and Memory July 1, 2015 T Nielsen, C O'Reilly, M Carr et al.
Overnight improvement on two memory tasks was linked to different sleep stages, challenging existing models of sleep-dependent learning. Participants who improved on the Corsi Block Tapping task had more REM sleep, while those who improved on the Tower of Hanoi task had more N2 sleep. Sleep spindle density was associated with Tower of Hanoi improvement, and spindle amplitude with Corsi Block improvement. The number of REM awakenings for dream reporting was linked to Corsi Block improvement but was confounded with total REM sleep time. The findings suggest capacity limitations on REM sleep and indicate that experimental awakenings for dream sampling may not disrupt—and might even enhance—sleep-dependent learning.