Fig. 5.

Subjective Sleepiness, Reaction Time, Lapses of Attention, and Attentional Failures Across 26 Hours of Wakefulness in Young and Older Participants. Group average data (+ standard error of the mean) are plotted with respect to time since scheduled awakening for 11 healthy older (mean age 68.1 ± 3.6 years; range 65 to 76 years; filled symbols) and 26 healthy young (mean age 21.9 ± 3.3 years; range 18 to 29 years; open symbols) adults. Dashed box indicates time of usual sleep episode. Subjective sleepiness ratings from the Karolinska Sleepiness Scale (KSS; scale range from 1=very alert to 9=very sleepy) are presented in Panel A. Mean reaction time (RT, in milliseconds) from each 10-minute PVT is presented in Panel B. As indicated in the first 16 hours of data, the RT on the PVT in well-rested individuals averages ∼250 milliseconds during the daytime, with minimal variability. The total number of lapses of attention (RT >500 milliseconds) from each 10-minute PVT are presented in Panel C. Well-rested individuals typically have very few (<5 per test administration) lapses of attention under these conditions. Attentional failures, defined as intrusions of slow eye movements (SEM) from continuous electro-oculographic recordings during EEG-verified wakefulness, were summed hourly and are presented in Panel D. Well-rested individuals typically have very few SEM under these conditions. Figure and legend reprinted with permission from: Duffy JD, Willson HJ, Wang W, Czeisler CA. J Am Geriatr Soc 2009; In Press. (⁵⁶).