Light suppresses melatonin secretion in humans.
Level 4 - case-series / case-control
Small non-randomized laboratory interventional study (n=6)
PubMed 7434030 · doi:10.1126/science.7434030
What was done
Six normal human subjects were exposed to bright artificial light and lower-intensity room light during the night to test whether light exposure suppresses nocturnal melatonin secretion.
What was found
No quantitative numbers, intensity values, or statistical metrics were reported in the abstract. Bright artificial light suppressed nocturnal melatonin secretion in all six subjects, whereas ordinary room light of lesser intensity did not.
Why it matters
This study showed that human melatonin secretion is sensitive to light suppression when the light is sufficiently bright, demonstrating a response qualitatively similar to other mammals.
Limits
The sample size is very small (n=6). The abstract omits precise light intensities, exposure durations, participant demographics, and numerical melatonin levels.
Cited by
- supports Bright light and blue light suppress melatonin production.