Daily fluctuations in sleep duration and quality affect next-day processing speed performance in young and older adults: an intensive longitudinal everyday life study over 21 days

Daily fluctuations in sleep duration and sleep quality are linked to processing speed in young and older adults in real-world contexts. Results suggest that within-person, day-to-day variations in sleep may be more important than between-person differences. Maintaining an adequate sleep duration each day may help prevent cognitive impairments in daily functioning across age groups.