Abstract
Sleep slow waves are studied for their role in brain plasticity, homeostatic regulation, and their changes during aging. Here, we address the possibility that two types of slow waves co-exist in humans. Thirty young and 29 older adults underwent a night of polysomnographic recordings. Using the transition frequency, slow waves with a slow transition (slow switchers) and those with a fast transition (fast switchers) were discovered. Slow switchers had a high electroencephalography (EEG) connectivity along their depolarization transition while fast switchers had a lower connectivity dynamics and dissipated faster during the night. Aging was associated with lower temporal dissipation of sleep pressure in slow and fast switchers and lower EEG connectivity at the microscale of the oscillations, suggesting a decreased flexibility in the connectivity network of older individuals. Our findings show that two different types of slow waves with possible distinct underlying functions coexist in the slow wave spectrum.
Highlights
Sleep slow waves are Non-Rapid Eye Movement (NREM) sleep oscillations in the delta range (
Our analyses demonstrated the existence of the “slow switchers” and the “fast switchers” represented by a bimodal distribution of the transition frequency, in each cluster and for both young and older individuals (Figure 3B and 3C)
We showed that older individuals had a higher probability of producing slow switchers than fast switchers when generating a slow wave compared to younger individuals
Summary
Sleep slow waves are Non-Rapid Eye Movement (NREM) sleep oscillations in the delta range (
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