1 Sleep, Cognition and Neuroimaging Laboratory, Concordia University, Montreal, QC, CA.
2 Department of Health, Kinesiology, and Applied Physiology, Concordia University, Montreal, QC, CA.
3 PERFORM Center, Concordia University, Montreal, QC, CA.
4 Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, QC, CA.
5 Department of Psychology, Concordia University, Montreal, QC, CA.
6 Département des Sciences de l'activité physique, GRAPA, Université du Québec à Montréal, Montréal, QC, CA.
7 Department of Medicine and Centre de recherche de l'Institut de cardiologie de Montréal, Université de Montréal, QC, CA.
8 Centre de recherche, CIUSSS du Nord-de l'Île-de-Montréal, Montréal, QC, CA.
9 School of Psychology and Neuroscience, University of Glasgow, UK.

Recent evidence shows that a nap and acute exercise synergistically enhanced memory. Additionally, human-based cross-sectional studies and animal experiments suggest that physical exercise may mitigate the cognitive impairments of poor sleep quality and sleep restriction, respectively. We evaluated whether acute exercise may offset sleep restriction's impairment of long-term declarative memory compared to average sleep alone. A total of 92 (82% females) healthy young adults (24.6 ±4.2 years) were randomly allocated to one of four evening groups: sleep restriction only (S5, 5-6 hours/night), average sleep only (S8, 8-9 hours/night), high-intensity interval training (HIIT) before restricted sleep (HIITS5) or HIIT before average sleep (HIITS8). Groups either followed a 15-minute remote HIIT video or rest period in the evening (7:00 p.m.) prior to encoding 80 face-name pairs. Participants completed an immediate retrieval task the same evening and a delayed retrieval task the next morning, after their respective sleep opportunities (documented subjectively). Long-term declarative memory performance was assessed with the discriminability index (d') during the recall tasks. We found that the d' of S8 (0.58 ±1.37) was not significantly different from those of HIITS5 (-0.03 ±1.64, p = 0.176) and HIITS8 (-0.20 ±1.28, p = 0.092), except the S5 (-0.35 ±1.64, p = 0.038) at the delayed retrieval. Similarly, the d' of HIITS5 was not significantly different from those of HIITS8 (p = 0.716) and S5 (p = 0.469). These results suggest that the acute evening HIIT partially reduced the detrimental effects of partial sleep restriction on long-term declarative memory.