You probably know what it feels like the morning after a night of bad sleep: you’re moving slower than usual and your mind just doesn’t want to get down to business. Although you understand how not getting enough shut-eye seems to disturb your day, you may not have considered the specific impact on your memory. According to new research from a team of researchers at UC Irvine, too little sleep may increase your susceptibility to forming false memories. "Recent studies are suggesting that people are getting fewer hours of sleep on average, and chronic sleep deprivation is on the rise," says Dr. Steven J. Frenda, psychologist at UC Irvine. "Our findings have implications for the reliability of eyewitnesses who may have experienced long periods of restricted or deprived sleep."

Implications for Eyewitnesses

Frenda and his colleagues began their study of sleep deprivation and memory by conducting a few preliminary experiments which showed a link between restricted sleep (five hours or less) and the formation of false memories. Based on this finding, the team designed an experiment to explore whether or not pulling an all-nighter increased the likelihood of forming false memories. They began by enlisting the help of 104 college-age participants and immediately dividing them into four groups. Then they asked the participants to return for an evening session in the lab.

As soon as two of the groups arrived, the researchers asked them to view a series of photos depicting a crime being committed. Then, one of the groups was allowed to sleep, while the other group remained awake all night. Meanwhile, the two other groups performed all of these same steps in reverse order; one group slept while the other stayed awake all night, and then both groups viewed the crime photos in the morning.

After completing this first part of the experiment, the participants read narratives about the crime containing statements that clearly contradicted what the photographs showed. One statement, for example, indicated the thief put a stolen wallet in his pants pocket, whereas the photo showed him putting it in his jacket. Finally, the researchers tested all the participants’ memories of the crime.

The memory tests provided surprising results: Only one group of the four was most likely to report having seen the false details from the text in the crime photographs. The participants who had been sleep deprived for all parts of the experiment — those who stayed up all night and then viewed the photos, read the narratives, and took the memory test — were most likely to report the false details. However, the participants who had viewed the photos before staying up all night were no more susceptible to false memories than the two groups of students who'd been allowed to sleep.

While the implications may appear significant, Frenda believes more research is necessary before he and his colleagues would be able to provide law enforcement with evidence-based guidelines on how to best ensure that eyewitnesses' memories are accurate. "We are running new experiments now, in order to better understand the influence of sleep deprivation on processes related to false memory," he says.

Source: Frenda SJ, Patihis L, Loftus EF, Lewis HC, Fenn KM. Sleep Deprivation and False Memories. Psychological Science. 2014.