New research by Zlatan Krizan, Breanna Curran and Richard Leo, published in Psychology, Public Policy, and Law, argues that US courts should recognise the risks of relying on statements and confessions from people who are very tired. The authors find that people involved with police often have poorer and more disrupted sleep than the general population, and that interviews and interrogations commonly occur at night or after long waits, so tiredness frequently affects questioning.
The review sets out three stages where sleep‑related impairment can distort evidence: before reporting an event (fatigue weakens memory), during initial contact (tired people may be less clear or engaged) and during custodial questioning (fatigue increases vulnerability to pressure and to false confessions). The authors note specific effects: reduced autobiographical detail, greater susceptibility to misinformation and leading questions, stronger feelings of overwhelm in stressful situations, and, in extreme cases, confusion that can make people doubt their own memories and internalise false information.
- Low-to-moderate impairment: 24 hours without sleep, or only four hours per night over two days; this level exceeds the legal limit for blood alcohol concentration in most states and raises the risk of false confessions under accusatorial tactics.
- High impairment: 48 hours without sleep, or only four hours per night over four days; this produces significant cognitive and emotional impairment and exceeds the 36‑hour nonstop threshold the US Supreme Court has called inherently coercive.
- Extreme impairment: 72 hours without sleep, or only four hours per night over one week; this can cause psychosis and extreme physiological disruption.
The researchers recommend documenting interview timing and duration, noting signs of fatigue, using routine video recording, and developing protocols and legal standards that account for sleep disruption. They also call for more research on how tiredness affects decision‑making, stress and confidence in memory, since sleep loss can change the reliability of evidence on which justice depends.
Difficult words
- impairment — reduced ability to think or perform tasks
- interrogation — formal questioning by police or investigatorsinterrogations
- custodial — relating to detention or police custody
- misinformation — false or misleading information that changes memory
- coercive — using force or pressure to change behaviour
- psychosis — serious mental condition with loss of reality
- protocol — written procedures for standard practice or actionprotocols
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Discussion questions
- How might documenting interview timing and signs of fatigue change the outcome of a legal case?
- What practical difficulties could police face if they try to avoid questioning people when they are tired?
- What kinds of further research about sleep and memory would help courts evaluate witness statements?
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