Melatonin Suppression by Light in Humans Is More Sensitive Than Previously Reported.
Level 4 - case-series / case-control
Human laboratory physiological experimental study reported in a brief communication without trial design details in the abstract.
PubMed 26017927 · doi:10.1177/0748730415585413
What was done
The authors applied an experimental protocol designed to increase data precision to reassess the sensitivity threshold for light-induced melatonin suppression in humans exposed to 460-nm blue light. The abstract does not provide specific details regarding participant selection, sample size, exposure duration, or control conditions.
What was found
The threshold for human melatonin suppression at 460 nm was found to be ~10 log photons cm⁻² s⁻¹, compared to the previously accepted threshold of ~12 log photons cm⁻² s⁻¹.
Why it matters
These findings suggest that the human circadian system is approximately two orders of magnitude more sensitive to nocturnal blue-light exposure than previously recognized, meaning lower light levels can trigger melatonin suppression.
Limits
The abstract does not disclose sample size, demographics, statistical variability, duration or timing of light exposure, or whether pupils were dilated. Because this is presented in a letter, complete experimental and analytical details are omitted from the record.
Cited by
- supports Exposure to even a small amount of light, particularly blue light, disrupts nocturnal melatonin release.