Sleep plays a key role in the formation and retention of facts and experiences. It makes sense, then, that memory recall declines when we lose sleep. According to a new study, published in the Proceedings of the National Academy of Sciences, a sleep-starved person is not only less likely to remember what happened, but also more likely than their well-rested counterpart to admit to events that never happened to them in the first place.
Researchers from Michigan State University, The New School and UC Irvine studied the connection between sleep deprivation and false memories in the context of false confessions. They found that people who stayed up all night were considerably more likely to sign a statement including a false allegation than those who reviewed the statement after hitting their #hardeight. What’s more, researchers believe that impulsive people are especially vulnerable to accepting revisionist histories when they go without sleep.
False confessions contribute to as much as a quarter of wrongful convictions. And 17 percent of the time, according to one 2007 survey of police investigators' interrogation beliefs and practices, suspects cough them up during typical sleeping hours — midnight to 8 a.m. What’s more, analysis of known false confessions suggests a substantial chunk take place following interrogations lasting 24 hours or longer.
We know that emotionally and physically exhausted people make for more pliable interrogation subjects (sleep deprivation is a well-documented torture tactic). However, research suggests that the sleep-deprived don’t merely confess to crimes they didn’t commit because they’re desperate to leave interrogation rooms. Rather, sleep deprivation appears to interfere with their ability to trust their own recollections. As a result, they accept someone else’s version of what happened.
Sleep and Memory
Sleep, particularly the slow-wave stuff, is critical to memory consolidation, the process of converting short-term knowledge into longer-term memories. Research consistently shows a relationship between sufficient, high-quality sleep and accurate recollection. This link appears to be especially important when it comes to declarative memory, which refers to memories that can we can consciously recall.
Declarative memory further breaks down into semantic memory, which concerns facts we can learn and recite, and episodic memory, the recollection of personal experiences. When it comes to sleep deprivation and false confessions, we’re dealing with episodic memories.
In the current study, researchers set up an experiment to see how readily sleep-deprived and well-rested people admitted to false allegations. In this case, all participants completed various computer tasks over the course of three separate sessions. During the tasks, participants were repeatedly told not to press the Escape key. If they pressed it, researchers said, important study data would be lost.
After the second session, half the participants stayed up all night while the other half retired to lab bedrooms for eight hours. The following morning, participants received individualized statements, supposedly written by researchers observing the study, that described their behavior during the tasks. Participants were instructed to read and sign the statements to vouch for their accuracy.
The statements, however, weren’t accurate — they falsely said that every participant in question had pressed the Escape button. Half of the sleep-deprived group signed away, without objecting to the button-pressing allegations, compared to 18 percent of those who’d gotten sleep. Anyone who declined was shown (by a computer) the statement a second time. All told, 39 percent of the well-rested group and 68 percent of the sleep-deprived group admitted to pressing the forbidden button.
Obviously, the experimental situation hardly resembles an authentic police interrogation. But study authors believe that the set-up shows how vulnerable the sleep-deprived are to signing away their innocence. Researchers considered the possibility that the sleep-deprived participants admitted to hitting the Escape because they didn’t take time to read and understand the statements. So, researchers asked participants to demonstrate reading comprehension; all but two passed.
Based on personality tests, researchers also identified impulsiveness as a personality trait that increases a sleep-deprived person’s risk of giving a false confession. Sleep deprivation, study authors wrote, “sets the stage for a false confession by impairing complex decision making abilities — specifically, the ability to anticipate risks and consequences, inhibit behavioral impulses and resist suggestive influences.” So, naturally impulsive people are that much more likely to screw themselves over.
The study has implications for interrogation policies. In the study, researchers recommended that interrogators assess suspects' sleep habits leading up to interrogation and measure their sleepiness levels during the interrogation itself.
So one small step for sleep deprivation could be a giant leap for criminal justice. But, there’s a lot more to learn about sleep and spinning lies for this to stick. How, for example, does sleep deprivation affect a suspect's likelihood of signing a true confession?