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Healthy older adults appear more resilient to sleep loss relative to younger adults, particularly with respect to the likelihood of falling asleep. We examined task-dependent differences in age-related vulnerability to sleep deprivation focussing on outcomes reflecting sleep initiation (microsleep, SEMs, EEG delta power, long lapses > 3sec) versus other non-sleep-initiation aspects of impairment (mean RT/lapses, reflexive attention and inhibitory control). Seventeen younger (M =24.5±3.2years [range 21-33years], 10 males) and seventeen older (M=57.3±5.2years [range 50-65years], 9 males) healthy adults underwent 26 hours of sleep deprivation. Test batteries (Psychomotor Vigilance Test [PVT], Karolinska Drowsiness Test, Ocular Motor Paradigms) with simultaneous EEG were administered at regular intervals throughout. During sleep deprivation, younger adults had significantly more sleep initiation events relative to older adults (p<0.031) including EEG microsleep (average 4.4 vs 1.1), SEMs (10.7 vs 4.9) and relative delta power (38.1 vs 24.2%). For non-sleep initiation outcomes, interaction effects were not observed. Both younger and older groups had slower reflexive attention (4.2 and 3.1msec, respectively) and poorer inhibitory control (8.6% and 9% more errors) during sleep deprivation relative to when well-rested (p<0.001), with older adults being more impaired than younger adults overall (p<.001). Large inter-individual differences in sleep initiation events were observed for younger adults. Preliminary results suggest women exhibited age-related differences in all sleep initiation events (Hedges g=0.73-1.64), while men did not (g=0.12-0.34). Younger adults are more likely to fall asleep during sleep deprivation, particularly women, while older adults may be more likely to exhibit attentional control difficulties. |
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