Another key piece of evidence regarding SWS's involvement in declarative memory consolidation is a finding that people with pathological conditions of sleep, such as insomnia, exhibit both reduction in Slow-Wave Sleep and also have impaired consolidation of declarative memory during sleep [REF].
Some researchers suggest that sleep spindle, a burst of brain activity occurring during stage 2 sleep, plays a role in boosting consolidation of declarative memories [REF].