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The Claim

A study led by Yadan Li at Southwest University in Chongqing found that exposure to frightening images and sounds at night (20:00) produced greater increases in skin conductance, heart rate, and blood pressure than the same exposure during the day (08:00), regardless of room lighting conditions.

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The Short Version

Li et al. did find stronger skin conductance and heart-rate responses to frightening stimuli at night versus day, but the study did not measure blood pressure, did not report 20:00/08:00 as the test hours, and did not establish that the effect is independent of room lighting. These unsupported additions materially overstate the original findings.

Caveats

  • Blood pressure was never measured in the cited study.
  • Exact times of 20:00 and 08:00 are not documented in the source.
  • The independence of the effect from room lighting was not demonstrated; illumination was a separate variable with unclear interaction.

The Receipts

  1. Night or darkness, which intensifies the feeling of fear? - PubMed

    PubMed

  2. Light and Cognition: Roles for Circadian Rhythms, Sleep, and Arousal - Frontiers

    Frontiers in Neuroscience

  3. Predicting Individuals' Experienced Fear From Multimodal Physiological Responses to a Fear-Inducing Stimulus - PMC

    PMC

  4. Evidence of Differences in Diurnal Electrodermal, Temperature, and Heart Rate Patterns by Mental Health Status in Free-Living Data - medRxiv

    medRxiv

  5. Circadian Rhythms in Fear Extinction Recall Depend on the Time of Day of Extinction Recall, Not the Time of Day of Extinction Learning - PubMed

    PubMed

  6. Influence of time of day on psychological responses to exercise. A review - PubMed

    PubMed

  7. Twenty-four hour Skin Conductance in Panic Disorder - PMC

    PMC

  8. Dynamic effects of sleep deprivation on emotional behavior, circadian rhythm genes, and inflammatory infiltration in the medial prefrontal cortex - Frontiers

    Frontiers

  9. A more generalized fear response after a daytime nap - PubMed

    PubMed

  10. Time of Day-Dependent Alteration of Hippocampal Rac1 Activation Regulates Contextual Fear Memory in Rats - Frontiers

    Frontiers

+ 6 more sources — see the full list on Lenz

Filed Under

Chongqingcircadian rhythmSkin ConductanceSouthwest UniversityYadan Li

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