A recent study published in Experimental brain research shed new light on how total sleep deprivation affects the brain’s ability to process and integrate multiple stimuli presented in rapid succession. Researchers found that a full day without sleep significantly impairs attentional and temporal integration mechanisms. In other words, going without sleep for an entire day seriously hampers our ability to pay attention and quickly process information, which is crucial for properly responding to the rapid changes around us.
Humans have a limited ability to process multiple events when they occur simultaneously or in rapid succession. This limitation is evident in a phenomenon known as the attentional blink. Attentional blinking is the difficulty people have in identifying the second of two stimuli presented close together in time. The study aimed to explore how total sleep deprivation affects this phenomenon, given the known effects of sleep loss on various aspects of attention and perception.
“Initially, as a student, I was interested in studying the brain. After joining the Psychophysiology Laboratory, I had the opportunity to delve into other subjects that interested me a lot, such as biological rhythms and sleep, or the limits of human neuropsychological capacities such as attention and memory. said study author Carlos Gallegos of the Autonomous University of Nuevo León.
To understand how total sleep deprivation affects attention, researchers designed an experiment involving 22 undergraduate students. These students, aged around 17, did not present any health or sleep problems. The study ensured that they followed a regular sleep schedule before participating. They stayed in a laboratory for six consecutive days, subjected to different conditions to test their attention under different levels of sleep.
The experiment was divided into three main phases: For two nights, participants slept at least 8 hours to establish their normal attention level. On the fourth day, participants stayed awake for 24 hours straight. Participants were allowed to sleep freely for two nights to see if their attention levels returned to normal.
The researchers used a task called Rapid Serial Visual Presentation (RSVP) to measure attention. In this task, participants had to identify two target numbers shuffled among a series of distractor letters displayed quickly on a computer screen. The accuracy of identifying these numbers at different time intervals made it possible to measure the attentional blink.
After 24 hours without sleep, participants’ ability to accurately identify target digits decreased significantly. This drop in performance was restored after participants had two nights of unrestricted sleep, indicating that sleep is crucial for maintaining attention.
Sleep deprivation prolonged the time participants struggled to identify the second target number. Normally, the attentional blink occurs at intervals of 200 to 500 milliseconds, but the sleep-deprived participants had difficulty even at 600 milliseconds. This expansion suggests a significant alteration in the brain’s ability to quickly process successive stimuli.
“The main takeaway is that skipping a night of sleep can increase the risk of making mistakes,” Gallegos told PsyPost. “While some mistakes are harmless (like misreading a word while studying), others can be fatal (like pressing the accelerator instead of the brake while driving). It is important to emphasize that when we push abilities such as attention and memory to their limits (as happens in Attentional Blinking), there is always a risk of error, even during the day or without deprivation sleep.
Attentional blink magnitude, which measures the extent to which second target identification accuracy declines during the attentional blink interval, was reduced during sleep deprivation. This reduction was mainly due to an overall drop in accuracy for both targets, particularly the second. The magnitude of attentional blinks returned to normal levels after recovery sleep, highlighting the temporary but serious impact of sleep deprivation.
Under normal conditions, if the second target appears very shortly (within 100 milliseconds) after the first, both are usually identified correctly – a phenomenon known as lag 1 sparing. However, this effect disappeared during sleep deprivation, indicating an impairment of temporal integration mechanisms. This means that the brain’s ability to process and integrate information presented in rapid succession has been compromised.
Participants also made more errors identifying target numbers in the wrong order during sleep deprivation, particularly in intervals of up to 400 milliseconds. This increase in order reversals suggests that sleep deprivation prolongs the period during which the brain integrates multiple stimuli, leading to confusion.
“In our task to measure attentional blinking, stimuli were presented quickly, individually and successively, and participants had to identify two numbers (targets) among the letters (distractors),” Gallegos explained. “When stimuli appear in direct succession (with no distractions in between), people often identify the first stimulus as the second and vice versa. This reversal in the order of stimuli is even greater in cases of sleep deprivation. This result suggests that there are certain alterations in perception that could lead to errors in selecting (attending) the correct stimulus.
These findings have significant implications for people who frequently experience sleep deprivation, such as healthcare professionals, pilots, and others in high-stakes jobs. The study suggests that even after 24 hours of wakefulness, individuals’ ability to deal with rapid changes in their environment is severely compromised. This deficiency increases the risk of errors in tasks that require rapid responses.
“Pushing functions such as attention and memory to their limits can be dangerous during the day, even with adequate sleep,” Gallegos noted. “The risk increases during the night and with lack of sleep. Nowadays, it is very common, especially with the use of technology, for people to multitask. This is a very common way to push our processes to the extreme. »
“During research on the limits of attention, we learned that there are limits in other fundamental processes that operate simultaneously, such as perception and memory. I would like to further study the limits of these abilities and better understand how these functions relate to each other.
“I hope that in the future, society will place more value on these two fairly common topics,” Gallegos added. “On the one hand, sleep, which is a necessity that we often neglect to meet the demands of daily life. On the other, the limit of cognitive abilities, which we also frequently push back when we engage in various activities simultaneously.
The study titled “Total Effects of Sleep Deprivation on Attentional Blink” was authored by Carlos Gallegos, Candelaria Ramírez, Aída García, Jorge Borrani and Pablo Valdez.