Rods-cones and melanopsin detect light and dark to modulate sleep independent of image formation

C. M. Altimus, A. D. Güler, K. L. Villa, D. S. McNeill, T. A. LeGates, S. Hattar

Research output: Contribution to journalArticlepeer-review

168 Scopus citations


Light detected in the retina modulates several physiological processes including circadian photo-entrainment and pupillary light reflex. Intrinsically photosensitive retinal ganglion cells (ipRGCs) convey rod-cone and melanopsin-driven light input to the brain. Using EEGs and electromyograms, we show that acute light induces sleep in mice during their nocturnal active phase whereas acute dark awakens mice during their diurnal sleep phase. We used retinal mutant mouse lines that lack (i) the ipRGCs, (ii) the photo-transduction pathways of rods and cones, or (iii) the melanopsin protein and showed that the influence of light and dark on sleep requires both rod-cone and melanopsin signaling through ipRGCs and is independent of image formation. We further show that, although acute light pulses overcome circadian and homeostatic drives for sleep, upon repeated light exposures using a 3.5 h/3.5 h light/dark cycle, the circadian and homeostatic drives override the light input. Thus, in addition to their known role in aligning circadian physiology with day and night, ipRGCs also relay light and dark information from both rod-cone and melanopsin-based pathways to modulate sleep and wakefulness.

Original languageEnglish (US)
Pages (from-to)19998-20003
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number50
StatePublished - Dec 16 2008
Externally publishedYes


  • Circadian photo-entrainment
  • Intrinsically photosensitive retinal ganglion cell
  • Masking
  • Photoreceptor and opsin

ASJC Scopus subject areas

  • General


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