Demonstration of additivity failure in human circadian phototransduction.

Nov 3, 2005Neuro endocrinology letters

Failure of combined light signals to add up in human body clock responses

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗

Abstract

Melatonin suppression from filtered 436 nm light was greater than from broader mercury lamp illumination at equal irradiance levels.

Filtered illumination at 436 nm produced more melatonin suppression than the mercury lamp, despite equal levels of light exposure at that wavelength.
The findings suggest that the response to light in regulating melatonin may not be simply additive.
Evidence from neuroanatomy supports the idea that spectral opponency is important in human circadian phototransduction.

AI simplified

OBJECTIVES: Published data, both on nocturnal melatonin suppression in humans and on widely accepted retinal structure and function, suggest that spectral opponency plays a role in human circadian phototransduction. We directly test subadditivity, implied by spectral opponency, in human circadian phototransduction in response to nearly monochromatic and to polychromatic light.

METHODS: Adult male human subjects were exposed for 60 minutes to two intensities each of two lighting conditions, during nighttime experimental sessions. One condition consisted of light from mercury vapor lamps (450 and 1050 lx), and one condition consisted of light from these lamps filtered such that only the spectral line from this lamp at 436 nm was presented to subjects (7.5 and 15 lx).

RESULTS: Melatonin suppression from the filtered illumination at 436 nm alone was greater than mercury lamp illumination (containing energy at 436 nm in addition to other wavelengths), even when the sources exposed subjects' retinae to equal amounts of irradiance at 436 nm.

CONCLUSION: This direct test of subadditivity, together with evidence from neuroanatomy, supports the inference that spectral opponency is a fundamental characteristic of human circadian phototransduction.

Demonstration of additivity failure in human circadian phototransduction.

Abstract

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief