Sleep Deprivation Raises Concerns About Reliability of Legal Statements

Iowa State researchers examine the impact of fatigue on confessions and witness testimony

Published on Mar. 5, 2026

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A new research synthesis from Iowa State University researchers examines how sleep deprivation can affect the reliability of statements and confessions in the legal system. The study finds that sleep-related fatigue can distort what people say at various stages of legal proceedings, from weakening memory before reporting an incident to making someone more vulnerable to pressure during questioning. The researchers propose evidence-based benchmarks to help judges and investigators recognize and account for sleep disruption.

Why it matters

The research highlights a significant gap in the legal system's understanding of how sleep loss can impact the reliability of evidence, from eyewitness accounts to confessions. Addressing this issue is crucial for ensuring fairness and due process, as sleep-deprived individuals may be more prone to memory errors, false confessions, and other problematic outcomes.

The details

The study found that sleep loss can weaken eyewitness recall, reduce autobiographical detail, and increase susceptibility to misinformation and leading questions. Extreme fatigue can also make stressful situations like interrogations feel overwhelming, leading people to focus on getting out of the moment rather than the long-term consequences, which can push them toward complying or even internalizing false information.

  • Many police interviews take place at night, when people are naturally at a low point in alertness.
  • In a 1944 Supreme Court ruling, 36 hours of nonstop interrogation was deemed "inherently coercive".

The players

Zlatan Krizan

Professor of psychology at Iowa State University and lead author of the research synthesis.

Breanna Curran

Fourth-year doctoral student in social psychology at Iowa State University and co-author of the research synthesis.

Richard Leo

Professor of law and psychology at the University of San Francisco School of Law and co-author of the research synthesis.

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What they’re saying

“Many people who interact with the justice system - from suspects to witnesses - are exhausted, anxious and significantly sleep-deprived. These factors can affect the statements people give.”

— Zlatan Krizan, Professor of psychology at Iowa State University (Mirage News)

“Awareness is growing that sleep deprivation can distort what people say in legal proceedings, but research on fatigue's impact still lags behind.”

— Zlatan Krizan, Professor of psychology at Iowa State University (Mirage News)

What’s next

The researchers propose three evidence-based benchmarks to help judges and investigators evaluate the impact of sleep disruption: low-to-moderate impairment (24 hours without sleep), high impairment (48 hours without sleep), and extreme impairment (72 hours without sleep). They recommend that investigators document when interviews occur, how long they last, and any signs of significant fatigue.

The takeaway

This research highlights the need for the legal system to better recognize and account for the impact of sleep deprivation on the reliability of evidence, from witness testimony to confessions. Addressing this issue is crucial for ensuring fairness and due process, as sleep-deprived individuals may be more prone to memory errors, false confessions, and other problematic outcomes.