Nocturnal Risk Assessment and Its Association With Anxiety Symptoms.

Area of Science:

• Psychology
• Neuroscience
• Human Physiology

Background:

• Human risk assessment (RA) involves threat detection and analysis, potentially enhanced at night for protection.
• Enhanced nighttime RA may be linked to increased risk for anxiety disorders.
• Understanding time-of-day effects on RA is crucial for anxiety research.

Purpose of the Study:

• To investigate the hypothesis that nighttime enhances RA and its association with anxiety.
• To examine attentional and behavioral components of RA in response to different threat types (injury, infection) during day vs. night.

Main Methods:

• Healthy volunteers (N=87) were randomly assigned to daytime or nighttime lab sessions.
• Participants completed a novel task involving threat images (neutral, injury, infection) followed by lottery decisions.
• RA's attentional component was measured by threat-induced cardiac deceleration (bradycardia); behavioral component by risk aversion.
• Anxiety symptoms were assessed using the Depression, Anxiety, and Stress Scale (DASS-21).

Main Results:

• Nighttime participants showed sustained bradycardia to infection threat images, unlike daytime participants.
• Higher bradycardia to infection threat at night correlated with elevated anxiety symptoms.
• No significant nighttime enhancement was observed for injury threat bradycardia or risk aversion.
• The relationship between RA components and anxiety symptoms differed between day and night.

Conclusions:

• Time-of-day is a significant factor in human threat responses and anxiety risk.
• Nighttime may selectively enhance attentional orienting to infection-related threats, not all threats.
• Nocturnal RA enhancements are influenced by individual differences in anxiety levels.