Continuous wakefulness of short duration: Effects on psychomotor cognitive performance and subsequent sleep physiology

Objectives: It is not an uncommon situation that aircrews are exposed to continuous wakefulness and prolonged duty periods. The present study intended to understand the effects of continuous wakefulness of varying hours on psychomotor cognitive functions and physiological attributes of sleep. Material and Methods: In a repeated measure design, psychomotor cognitive functions were evaluated among 20 healthy aircrew during a period of forced wakefulness of 18 h by CogScreen aeromedical edition on three successive sessions; 1 st (baseline) at 0800–0900 h, 2 nd at 1900–2000 h and 3 rd at 2300–0000 h. The sleep architecture and bio-physiological parameters were studied with Alice 5 Polysomnography System® in the subsequent sleep period following 18-h of continuous wakefulness. Results: Consistent improvements in performance were observed in many tasks as a result of repetitive practice effects. The speed measures pertaining to computational math skills, reading comprehension and logical reasoning, sustained attention, and visual motor tracking were significantly affected in the 3 rd session compared to the 2 nd session. Similarly, there was a significant decrement in immediate and delayed visual paired associate memory in the 3 rd session compared to 2 nd session, whereas spatial processing and visual working memory showed a significant longitudinal decrement in accuracy scores across the period of wakefulness. The sleep architecture and the bio-physiological variables of sleep were found to be within the normal physiological limits. Conclusion: Few aspects of higher cognitive functions were adversely affected during continuous wakefulness of 18 h, even though such a period was not found to affect sleep architecture and bio-physiological variables of sleep.