AGE AND TIME IN BED EFFECTS ON MAINTENANCE OF WAKEFULNESS TEST-MEASURED DAYTIME SLEEPINESS AND PERFORMANCE

Daytime sleepiness in adolescents reflects both insufficient sleep and neurodevelopmental processes. We used available data from a large ongoing study to evaluate Maintenance of Wakefulness Test (MWT)-measured daytime sleepiness and performance in two different age groups under different experimental designs. All participants (18 and 24 years; 6 subjects per group) completed two time-in-bed (TIB) schedules: 7 days of habitual TIB, 3 days of 8.5h TIB, and 4 days of either 7h TIB (sleep restriction) or 10h TIB (sleep extension). On the day following the polysomnographic recording night of each experimental design, Psychomotor Vigilance Test (PVT), Karolinska Sleepiness Scale (KSS), and MWT were administered four times at two-hour intervals. Significant effects of TIB (19.3min for 7h TIB vs. 26.2min for 10h TIB), MWT session, and their interaction on MWT latency were found. Although the age effect was not significant, a lower ability to remain awake was evident in 24-year-old group under both TIB conditions. MWT latency negatively correlated with KSS scores in 7h condition (r=−0.61). Sleep restriction was associated with a shorter MWT latency. Somewhat paradoxically, alertness decreased but PVT performance improved with age. Findings show that experimental design was effective while age effect was less pronounced. The consistently shorter MWT latency in older group may reflect that trajectory of MWT-measured sleepiness peaks not during adolescence, as does MSLT-measured sleepiness, but in early adulthood. The entire study covering a wider age range would enhance our understanding of age-related trajectories and underlying causes of adolescent daytime sleepiness.
Support: SRNSF Grant FR-23-7109.