The interaction between sleep and development on wake EEG oscillations

The amount of time previously spent awake or asleep strongly impacts the sleep electroencephalogram (EEG), especially slow waves during non-rapid-eye-movement (NREM) sleep. These effects on the sleep EEG meaningfully interact with age and to a lesser extent developmental disorders such as attention-deficit hyperactivity disorder (ADHD). We aimed to determine whether EEG oscillations during wakefulness were likewise affected by the interaction of sleep and development, using data collected from 163 participants 3-25 years old (62 female). We analyzed age- and sleep-dependent changes in two measures of oscillatory activity (amplitudes and density) and aperiodic activity (offsets and exponents). Finally, we compared wake EEG in children with ADHD (N=58) to neurotypical controls, with habitual good sleep quality required for inclusion. We found that oscillation amplitudes exhibited the same dynamics as sleep slow waves: decreasing with age, decreasing after sleep, and the overnight decrease decreasing with age. Strikingly, wake oscillation densities in the alpha band decreased overnight in children but increased overnight in adolescents and adults. Aperiodic measures were affected by both sleep and age albeit with minimal interaction. No wake measure showed significant effects of ADHD, suggesting that previously reported differences in patients may reflect uncontrolled variability in sleep quality rather than disorder-specific effects. While these results do not disentangle homeostatic from circadian effects, they underscore the need to control for sleep/wake history and measurement scheduling in all EEG experiments, especially when focusing on children and adolescents. Significance statement Most studies measuring EEG during wakefulness do not take into consideration prior sleep/wake history. Here, we show that wake EEG measures significantly differ when measured before or after sleep, and these effects are strongly dependent on age. Differences between pediatric populations may in fact be due to prior sleep quality or circadian rhythms rather than hypothesized group differences.