Modest loss of sleep raises email phishing risk

Irvine, Calif.  — Nearly a third of adults in the U.S. do not get enough sleep. A recent surge in attention to this issue raises serious concerns about its long-term health implications, and new research suggests that it can lead to hazardous outcomes, especially in the context of “phishing” emails.

University of California, Irvine neurobiologists examined this by focusing on the transition to Daylight Saving Time in the spring of 2026. As we all “spring forward,” we also lose up to one hour of sleep. The researchers found that even this minor reduction in sleep led to a sizable increase in the risk of falling prey to cybersecurity attacks. Their findings appear in the Proceedings of the National Academy of Sciences.

To test the effects of this modest loss of sleep, the researchers leveraged a cybersecurity awareness campaign for more than 11,000 employees of a large U.S. institution. Every few months, its information technology group sends emails that resemble those used in phishing attacks to see how many recipients click the links included in these simulated emails. It’s part of an ongoing effort to educate these employees about the risks associated with cybersecurity crimes.

Hazardous implications for decision-making

The results show that on the Monday after the transition, employees were 13% more likely to fall prey to the simulated attacks than on the previous Monday (a click rate of 17.76% vs. 15.56%). This shows that even a modest and acute loss of sleep has real-life implications for decision-making.

Estimated financial losses from cybercrimes in the U.S. alone exceeded $20 billion in 2025, according to the Federal Bureau of Investigation Internet Crime Complaint Center 2025 Annual Report, and an increase in risk has direct monetary implications for companies and individuals.

“There are several ways to contextualize our findings,” said Dr. Eitan Schechtman, an assistant professor in neurobiology & behavior at UC Irvine, and the lead researcher on this study. “First, they give us a peek into the effects of very minor sleep loss such as that incurred due to the transition to Daylight Saving Time, which is similar in scope to the kind of sleep loss that many of us experience daily. Although we focused on cybersecurity, many of our day-to-day decisions are likely compromised in similar ways. Better sleep likely leads to better decisions.”

Better aligning with our internal clock

Beyond the general effects of sleep loss, the results also inform the discussion on the biannual clock changes common in most states. The U.S. House of Representatives recently passed the Sunshine Protection Act, which would make Daylight Saving Time permanent throughout the U.S. Although a permanent clock would avoid the transition that leads to sleep loss, according to the researchers, scientific data strongly suggest that Standard Time better aligns with our internal clock, and scientists have encouraged Congress to adopt it as a permanent clock.

Regardless of the current debate, the results of the study emphasize that if these clock shifts continue, precautions should be taken to mitigate the risks.

“I hope that cybersecurity companies and employers will take action ahead of the Daylight Savings Time transition, as well as in other times during which sleep is compromised, such as following holidays or major sports events,” Schechtman said.  

Although the results have commercial and financial implications for society at large, they also bear important ramifications at the individual level.

“You don’t have to be a great sleeper to prioritize sleep,” Schechtman said. “For too many of us, sleep is an inconvenience, with some even taking pride in how little they sleep each night. Our results demonstrate that even though you may not be aware of it, lack of sleep leads to impulsive choices, and you may lose more than you gain from putting sleep on the back burner.”

About the Center for the Neurobiology of Learning and Memory: Established in 1983 by the UC Regents, with James L. McGaugh as its Founding Director, the CNLM is the first research institute in the world dedicated to the interdisciplinary study of the fundamental brain mechanisms of learning and memory. It is credited with numerous seminal discoveries about how memory works and is recognized as a global leader in the area. Led by Director Michael Yassa, the CNLM is home to more than 120 faculty scientists at UCI and beyond. The Center has also developed several successful training programs for neuroscience education at all levels and is deeply committed to enhancing diversity and inclusion in academia. For more information on the CNLM, visit cnlm.uci.edu.

About the University of California, Irvine: Founded in 1965, UC Irvine is a member of the prestigious Association of American Universities and is ranked among the nation’s top 10 public universities by U.S. News & World Report. The campus has produced five Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Howard Gillman, UC Irvine has more than 36,000 students and offers 224 degree programs. It’s located in one of the world’s safest and most economically vibrant communities and is Orange County’s second-largest employer, contributing $7 billion annually to the local economy and $8 billion statewide. For more on UC Irvine, visit www.uci.edu.