Study design. Following a screening and acclimatization night of PSG, participants returned 1 wk later to the laboratory for the experimental session. N = 20/group were assigned to either the sleep, nap, or wake group and underwent MRI imaging sessions to obtain resting-state fMRI BOLD images before training (rest 1), after training (rest 2), and after the retention interval but prior to retest (rest 3). In the sleep group, rest 1 began at ∼2100 h, and rest 2 began 20–30 min later (at ∼2130 h). The 8-h sleep opportunity began at ∼2200 h, and rest 3 began 10–11 h later (∼0900 h). In the nap group, rest 1 began at ∼1200 h, and rest 2 began 20–30 min later (at ∼1230 h). The 90-min sleep opportunity began at ∼1400 h, and rest 3 began 3 h later (∼1700 h). In the wake group, rest 1 began at ∼0900 h, rest 2 began 20–30 min later (at ∼0930 h), and rest 3 began 10–11 h later (∼2000 h). It is important to note that the intervals between sleep and wake were held constant. Participants in the wake group remained awake in between the training and retest sessions (confirmed via actigraphy).
