Work by day and sleep by night, do not sleep too little or too much: Effects of sleep duration, time of day and circadian synchrony on flanker-task performance in internet brain-game users from teens to advanced age.

Research elucidating the effects of sleep and circadian rhythm on cognitive performance is advancing, yet many important questions remain. Using flanker-task performance scores from a large internet sample (N = 48,881) with repeated measures of cognitive performance and linked prior-night self-reported sleep duration, we analysed the relationship between sleep duration, time of day of task performance, and chronotype synchrony with performance in participants aged 15-80 years. Results indicate a performance peak at 7 hr habitual sleep duration, and point to a variable effect of deviation from habitual sleep duration depending on users' habitual sleep duration and age. Time-of-day effects were notable for a steady decline in performance up until 01:00 hours-02:00 hours for the group as a whole, which was accounted for by nighttime deterioration on trials requiring inhibitory executive functioning, particularly in older subjects. Analyses did not demonstrate an advantage for playing in synchrony with self-identified chronotype. Results strengthen findings indicating an inverted U-shaped relationship between sleep duration and cognitive performance across a broad spectrum of age groups. These findings underscore the importance of daytime task performance for tasks requiring inhibitory function, especially in elderly people. Findings highlight the utility of large-scale internet data in contributing to sleep and circadian science.

MR Imaging for Assessing Injury Severity and Prognosis in Acute Traumatic Spinal Cord Injury.

T2-weighted (T2W) imaging is the most important sequence for detection of acute traumatic spinal cord pathology in clinical practice. Intramedullary hemorrhage on T2W imaging is associated with some component of irreversible injury and arguably the most robust MR imaging predictor of injury severity. The MR imaging appearance of the injured spinal cord in the early stages of injury is highly dynamic, and the time delay from injury to imaging must be considered in image interpretation. Diffusion imaging offers promise as specific tool for interrogating spinal cord integrity, although well-designed, prospective clinical studies validating its application remain limited.