Read the following passage from a scientific article on the effects of sleep deprivation on cognitive function.
"Prolonged sleep deprivation has been shown to impair various cognitive functions, including attention, memory, and decision-making. Studies indicate that individuals who sleep less than six hours per night for extended periods experience significant reductions in their ability to concentrate, retain information, and make sound judgments. Moreover, the negative effects of sleep deprivation are cumulative, meaning that even small nightly deficits can add up to substantial impairments over time. These findings underscore the importance of adequate sleep for maintaining optimal cognitive performance."
Which statement best summarizes the author's findings?