Science underestimated dangerous effects of sleep deprivation
November 21, 2019
Science Daily/Michigan State University
One of the largest sleep studies dubunks theory that suggests attention is the only cognitive function affected by sleep deprivation.
Michigan State University's Sleep and Learning Lab has conducted one of the largest sleep studies to date, revealing that sleep deprivation affects us much more than prior theories have suggested.
Published in the Journal of Experimental Psychology: General, the research is not only one of the largest studies, but also the first to assess how sleep deprivation impacts placekeeping -- or, the ability to complete a series of steps without losing one's place, despite potential interruptions. This study builds on prior research from MSU's sleep scientists to quantify the effect lack of sleep has on a person's ability to follow a procedure and maintain attention.
"Our research showed that sleep deprivation doubles the odds of making placekeeping errors and triples the number of lapses in attention, which is startling," Fenn said. "Sleep-deprived individuals need to exercise caution in absolutely everything that they do, and simply can't trust that they won't make costly errors. Oftentimes -- like when behind the wheel of a car -- these errors can have tragic consequences."
By sharing their findings on the separate effects sleep deprivation has on cognitive function, Fenn -- and co-authors Michelle Stepan, MSU doctoral candidate and Erik Altmann, professor of psychology -- hope that people will acknowledge how significantly their abilities are hindered because of a lack of sleep.
"Our findings debunk a common theory that suggests that attention is the only cognitive function affected by sleep deprivation," Stepan said. "Some sleep-deprived people might be able to hold it together under routine tasks, like a doctor taking a patient's vitals. But our results suggest that completing an activity that requires following multiple steps, such as a doctor completing a medical procedure, is much riskier under conditions of sleep deprivation."
The researchers recruited 138 people to participate in the overnight sleep assessment; 77 stayed awake all night and 61 went home to sleep. All participants took two separate cognitive tasks in the evening: one that measured reaction time to a stimulus; the other measured a participant's ability to maintain their place in a series of steps without omitting or repeating a step -- even after sporadic interruptions. The participants then repeated both tasks in the morning to see how sleep-deprivation affected their performance.
"After being interrupted there was a 15% error rate in the evening and we saw that the error rate spiked to about 30% for the sleep-deprived group the following morning," Stepan said. "The rested participants' morning scores were similar to the night before.
"There are some tasks people can do on auto-pilot that may not be affected by a lack of sleep," Fenn said. "However, sleep deprivation causes widespread deficits across all facets of life."
https://www.sciencedaily.com/releases/2019/11/191121183923.htm
Sleep readies synapses for learning
Findings offer insight into changes that occur in the brain during sleep
July 1, 2019
Science Daily/Society for Neuroscience
Synapses in the hippocampus are larger and stronger after sleep deprivation, according to new research in mice published in JNeurosci. Overall, this study supports the idea that sleep may universally weaken synapses that are strengthened from learning, allowing for new learning to occur after waking.
Sleep is thought to recalibrate synaptic strength after a day of learning, allowing for new learning to take place the next day. Chiara Cirelli and colleagues at the University of Wisconsin-Madison examined how synapses in the hippocampus, a structure involved in learning, changed following sleep and sleep deprivation in mice.
Consistent with previous studies in the cortex, the researchers observed that synapses were larger, and therefore stronger, after the mice were awake for six to seven hours compared to after they were asleep for the same amount of time. Additionally, the researchers found that the synapses were strongest when the mice were forced to stay awake and interact with new stimuli, compared to mice that stayed awake on their own. This is consistent with the hippocampus' role in learning, and suggests that synaptic changes take place when learning occurs, not merely from being awake.
https://www.sciencedaily.com/releases/2019/07/190701144310.htm
How sleep deprivation hinders memory
October 2, 2018
Science Daily/Michigan State University
Researchers have conducted the largest experimentally controlled study on sleep deprivation to date, revealing just how detrimental operating without sleep can be in everything from bakers adding too much salt to cookies to surgeons botching surgeries.
While sleep deprivation research isn't new, the level at which distractions hinder sleep-deprived persons' memories and challenge them from successfully completing tasks was not clear until MSU's team quantified the impact.
"If you look at mistakes and accidents in surgery, public transportation and even operating nuclear power plants, lack of sleep is one of the primary reasons for human error," said Kimberly Fenn, associate professor of psychology and director of the MSU Sleep and Learning Lab. "There are many people in critical professions who are sleep-deprived. Research has found that nearly one-quarter of the people with procedure-heavy jobs have fallen asleep on the job."
Published in the Journal of Experimental Psychology: General, Fenn's research is unlike previous studies because of its focus on sleep deprivation's impact on completing tasks. These tasks, Fenn explained, involve following directions and include multiple steps.
Some basic errors, such as adding salt twice to a recipe, might not be so serious. However, some of the world's greatest human-caused catastrophes -- like Chernobyl, the Exxon Valdez oil spill and the Challenger explosion -- along with daily train and car accidents have sleep deprivation at least partially to blame, she said.
Fenn hopes that her lab's findings will shed light on how critical sleep is to completing any task, be it large or small.
"Every day, approximately 11 sponges are left inside of patients who have undergone surgery. That's 4,000 potentially dire missteps each year and an example of a procedural task gone terribly wrong that can result from sleep deprivation," Fenn said. "Our research suggests that sleep-deprived people shouldn't perform tasks in which they are interrupted -- or, only perform them for short periods."
To test sleep deprivation's impact on how people follow steps in a task, Fenn's team brought 234 people into the sleep lab at 10 p.m. That night, all of the participants worked on a sequence-based procedure that involved following a series of tasks in order. Periodically, they were interrupted and had to remember where they were in the procedure before picking up again. At midnight, half of the participants went home to sleep while the other half stayed awake all night at the lab. The next morning, everyone completed the procedure once again.
What Fenn's team found was a stark jump in errors for those who were sleep-deprived.
"All participants met performance criteria in the evening, but roughly 15 percent of participants in the sleep-deprived group failed in the morning, compared to 1 percent of those who slept," Fenn said. "Furthermore, sleep-deprived participants not only showed more errors than those who slept but also showed a progressive increase in errors associated with memory as they performed the task -- an effect not observed in those who slept. This shows that the sleep-deprived group experienced a great deal of difficulty remembering where they were in the sequence during interruptions."
Memory maintenance, the research found, was the real culprit keeping the sleep-deprived from completing tasks successfully. With hindered memory maintenance, it's much more difficult to pick up a task where you left off without missteps, Fenn explained.
Fenn also explained that distractions we face every day -- whether receiving a text message or simply answering a question -- are unavoidable but especially harmful to sleep-deprived people.
"Operating with reduced cognitive capacity has wide-ranging effects," Fenn said. "Students may pull all-nighters and not retain information for their exams. More worrisome, individuals working critical jobs may put themselves and other members of society at risk because of sleep deprivation. It simply cannot be overlooked."
https://www.sciencedaily.com/releases/2018/10/181002114027.htm