When the sun prickles your nose: an EEG study identifying neural bases of photic sneezing

PLoS One. 2010 Feb 15;5(2):e9208. doi: 10.1371/journal.pone.0009208.


Background: Exposure to bright light such as sunlight elicits a sneeze or prickling sensation in about one of every four individuals. This study presents the first scientific examination of this phenomenon, called 'the photic sneeze reflex'.

Methodology and principal findings: In the present experiment, 'photic sneezers' and controls were exposed to a standard checkerboard stimulus (block 1) and bright flashing lights (block 2) while their EEG (electro-encephalogram) was recorded. Remarkably, we found a generally enhanced excitability of the visual cortex (mainly in the cuneus) to visual stimuli in 'photic sneezers' compared with control subjects. In addition, a stronger prickling sensation in the nose of photic sneezers was found to be associated with activation in the insula and stronger activation in the secondary somatosensory cortex.

Conclusion: We propose that the photic sneeze phenomenon might be the consequence of higher sensitivity to visual stimuli in the visual cortex and of co-activation of somatosensory areas. The 'photic sneeze reflex' is therefore not a classical reflex that occurs only at a brainstem or spinal cord level but, in stark contrast to many theories, involves also specific cortical areas.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Electroencephalography
  • Evoked Potentials, Somatosensory / physiology
  • Female
  • Humans
  • Light*
  • Male
  • Nose / physiology
  • Photic Stimulation
  • Reflex / physiology
  • Sneezing / physiology*
  • Somatosensory Cortex / physiology*
  • Sunlight
  • Visual Cortex / physiology*
  • Visual Perception / physiology
  • Young Adult