In people with progressive multiple sclerosis, brain function changes are not well understood, but studying them could reveal more about how the disease works at this stage.
During non-rapid eye movement (NREM) sleep, the brain's large-scale functional networks show a surprising pattern: nearly all networks are most active during NREM stage 2, then abruptly lose activity in NREM stage 3. However, despite this high activity in stage 2, the functional connections and mutual dependencies between networks progressively break down as sleep deepens. This means that even though networks attempt to communicate during stage 2, the efficiency of information transfer is low. The findings advance neural models of sleep and consciousness by showing that network integrity, not just activity levels, is crucial for conscious awareness.