Age-related vulnerability to sleep deprivation is task dependent and influenced by large inter-individual differences...

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 focusing on outcomes reflecting sleep-initiation (microsleep, slow eye movements [SEMs], electroencephalography [EEG] delta power, and long lapses > 3 s) versus other non-sleep-initiation aspects of impairment (adjusted mean RT/lapses, reflexive attention, and inhibitory control).

Seventeen younger (M = 24.5 ± 3.2 years [range 21-33 years], 10 males) and 17 older (M = 57.3 ± 5.2 years [range 50-65 years], 9 males) healthy adults underwent 26 h of sleep deprivation. Test batteries (psychomotor vigilance test [PVT], Karolinska drowsiness test, and 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 < .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 3.1 ms, respectively) and poorer inhibitory control (8.6% and 9% more errors) during sleep deprivation relative to when well-rested (p < .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 to 1.64), while men did not (g = 0.12 to 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.