22 Dec Morning People May Make More Mistakes After A Long Day
MedicalResearch.com Interview with:
Dr. Nicola Barclay, BA(Hons), MSc, PhD.
Lecturer in Sleep Medicine
Sleep and Circadian Neuroscience Institute (SCNi)
Nuffield Department of Clinical Neurosciences
Sir William Dunn School of Pathology
University of Oxford
MedicalResearch.com: What is the background for this study?
Response: We know that extreme sleep deprivation impairs our cognitive functions, particularly attention. This impairment in attention is likely to be driven by physiological mechanisms that change across the waking day (increasing sleep pressure), but also by factors associated with our biological clock. The timing of physiological processes particularly related to attention differ between morning and evening type people (our so called early morning larks and night owls), and so we hypothesised that morning and evening types would differ in their impairments in attention at different times of day, prior to and following 18 hours of sustained wakefulness.
MedicalResearch.com: What are the main findings?
Response: We examined 3 different components of attention (alerting, orienting and executive control) at two time points in 26 individuals who varied in their degree of morningness and eveningness. Participants were tested on the Attention Network Test at 8am following a normal night of sleep, and then again at 2am following 18 hours of sustained wakefulness. Contrary to expectation we found that morning types were faster overall in a global measure of attention at 2am than evening types.
However, morning types were more likely to make errors than evening types. When we examined the different components of attention separately we found that evening types outperformed morning types on measures of executive control which require the individual to inhibit or ignore conflicting information. This type of attentional process requires more cognitive effort and conscious control than other types of attention, which are more automatic.
MedicalResearch.com: What should readers take away from your report?
Response: After a long day of 18 hours of sustained wakefulness, morning types tend to adopt a fast reaction to cognitive tasks, but this is error prone. Thus, they sacrifice accuracy for speed. On the other hand, evening types may be slower in reacting to stimuli in their visual field, but they attend to such stimuli more accurately. In particular evening-types are better at resolving conflicting information that requires more conscious effort, than morning types, after a long day.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: We are planning to investigate the physiological mechanisms underlying these differences in attentional performance between morning and evening types. It is possible that these relative differences in performance are due to the timing of physiological mechanisms driving sleepiness and alertness, driven by the biological clock.
MedicalResearch.com: Is there anything else you would like to add?
Response: It is possible that the slower speed of response by evening types is due to an accumulation of sleep debt over the working week. We know that evening types are particularly vulnerable to ‘social jetlag’ which manifests as symptoms akin to jetlag. Social jetlag refers to the misalignment between the biological clock and time constraints imposed by social commitments. Evening types may be forced to awaken earlier in the morning to attend work, earlier than their biological clock would ordinarily dictate. Yet evening types often maintain a late bed time in line with their biological clock. Thus the sleep duration of evening types is often very short, resulting in a sleep debt which then accumulates over the working week.
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Sustained wakefulness and visual attention: moderation by chronotype
Barclay, N.L. & Myachykov, A. Exp Brain Res (2016). doi:10.1007/s00221-016-4772-8
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