Regularly cutting it short on sleep could have consequences beyond just feeling tired the next morning.
In the study, the rate of clicking on simulated phishing links was about 13 percent higher following the spring daylight saving time transition, when clocks move forward an hour, throwing off sleep schedules. Experts say that the findings raise questions about how seemingly minor sleep disruptions may affect everyday judgment.
“Most of us don’t think of checking email as something we need to be well-rested for,” says Michael Grandner, PhD, director of the Sleep and Health Research Program at the University of Arizona College of Medicine in Tucson, who was not involved in the study. “But it still requires us to notice small details and decide what to trust.”
Falling for Phishing Links Increased After the Time Change
Participants were randomly assigned to receive an unexpected phishing email on either the Monday before the time change or the Monday afterward, as part of an institutional cybersecurity awareness program.
The research team found that before the time change, about 16 percent of participants clicked on the suspicious link. After the time change, nearly 18 percent clicked on the link.
That means that overall, the proportion of people who clicked a simulated phishing link was about 13 percent higher after the spring time change than before it.
“It was somewhat surprising that such a minor and mundane change in sleep patterns — the kind that many of us would not see as harmful or unusual — had a sizable and measurable effect,” says lead study author Eitan Schechtman, PhD, an assistant professor of neurobiology and behavior at UC Irvine.
Still, the study had some limitations. Researchers didn’t directly measure sleep, so they couldn’t determine whether sleep loss specifically caused the increased phishing click rate. The study also points out that changes in circadian rhythms — the body’s internal clock — or morning light exposure may have contributed to the findings.
In addition, the findings came from a single institution, involved a single time change, and used simulated rather than actual phishing attacks, which limits how broadly they may apply.
Why Can Losing Sleep Affect Your Judgment?
“Your brain is doing a lot more than keeping you awake,” Dr. Grandner says. “It has to sort through information, decide what deserves your attention, keep track of what you’re doing, and catch mistakes.”
William “Scott” Killgore, PhD, a clinical neuropsychologist, research neuroscientist, and professor of psychiatry at the University of Arizona in Tucson, notes that much of the existing evidence comes from studies involving more substantial sleep deprivation. It’s unclear whether losing just one hour produces similar changes.
Dr. Killgore, who wasn’t involved in the new study, says that the study also leaves unanswered questions about why participants clicked on the suspicious links.
“We don’t really know if the deficits were in higher-level decision-making about the phishing emails, or whether the participants were experiencing lower alertness and the attentional lapses were causing them to miss critical information,” he says.
He also cautions against assuming that one lost hour of sleep will noticeably affect everyone’s decisions.
“For most healthy people, a single night with one less hour is not likely to meaningfully affect their decisions,” he says. “The greater danger emerges when one drastically cuts sleep for a night — for example, cutting out several hours — or is chronically obtaining less than their normal level of sleep.”
Raman Malhotra, MD, a professor of neurology and chief of sleep medicine at Washington University in St. Louis, adds that the effects of sleep loss vary among individuals, particularly those who are already sleep-deprived.
“There is always individual variation among the population, so there are people who are more likely and less likely to be affected by this one hour of sleep loss,” says Dr. Malhotra, who wasn’t involved in the research.
Losing Sleep Could Raise Risks Besides Phishing Scams
Although the study focused on cybersecurity, experts say that insufficient sleep can affect other aspects of daily life.
“Sleep loss can affect attention, memory, and emotional regulation, so the consequences can show up in several parts of your day,” Grandner says.
For example, insufficient sleep may make it harder to catch an incorrect amount on a bill, remember whether you’ve taken a medication, or interpret a coworker’s message accurately. Dr. Schechtman believes that the findings could also have implications for driving and impulse buying, although neither outcome was directly examined in the study.
Another concern is that people may not recognize when their performance is suffering. “It can be difficult to know how it is affecting you, as it may not be obvious,” Malhotra says. “The sleep loss itself can affect your brain’s ability to even properly judge how you are performing, or self-assessment.”
How to Get Enough Sleep and Avoid Mistakes When You’re Tired
Experts recommend prioritizing sufficient sleep and taking extra precautions on days when you’re not well-rested.
“I think just being aware that sleep loss can affect judgment is a good starting point,” Malhotra says.
To help avoid mistakes when you’re tired, consider these expert-recommended strategies:
- Aim for adequate sleep. Most adults need seven to nine hours per night, and keeping a consistent sleep schedule can help.
- Postpone major decisions when possible. Malhotra recommends waiting until you’re better rested before making important financial decisions or other consequential choices.
- Slow down and double-check details. Fatigue can increase mistakes, particularly under time pressure. “If something has to happen today, slow it down, do one thing at a time, and have someone else check the important details,” Grandner says.
- Be cautious with unexpected messages. Avoid clicking suspicious links. Instead, go to a company’s official app or website, or call a trusted phone number. “You don’t have to decide whether a suspicious link is safe in order to avoid using it,” Grandner says.
- Don’t rely on caffeine or naps alone. While these strategies may temporarily improve alertness, neither can fully compensate for sleep deprivation. “A person can drink coffee after limited sleep and feel like they are making good decisions, but often we find that they may just be making suboptimal decisions a bit faster and with a bit more enthusiasm,” Killgore says.
Although occasional sleep disruptions are inevitable, Schechtman says that getting adequate rest should remain a priority.
“The biggest takeaway is that even a minimal loss of sleep can have a noticeable impact on our daily cognitive performance,” he says. “I hope this encourages people to prioritize their sleep, rather than putting it on the back burner.”
