Number 9
Posts: 2091
Joined: May-31th-2008
From: Liverpool, England
Status: offline
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It's a proper thing that happens to some people. COPY & PASTE RULES!!!!! About 20-25% of people sneeze when they are exposed to bright light. The condition, if you can call it that, is referred to as the 'photic sneeze reflex'. There have been numerous explanations as to why it occurs including bright light making your eyes water and the tears irritating the nose, but this is almost certainly wrong because the sneezing kicks in too fast for tears to be formed. The US military carried out some studies on the photic sneeze reflex a few years ago because, obviously, it would be bad news for a fighter pilot travelling at 1000 mph to suddenly launch into a fit of sneezing. Their studies found that photic sneezing runs in families, and so presumably has a genetic origin. It also seems to be a neurological phenomenon. Exposure to bright light triggers a number of changes in the eyes including blinking, and pupil closure (constriction or meiosis). Pupilloconstriction is controlled by the brainstem which is an interface linking the spinal cord to the rest of the brain and contains many vegetative control centres which co-ordinate breathing, heart rate, blood-pressure, arousal, sleep and dreaming, and many other functions. It's therefore likely that in people with this sneeze reflex there is a bit of crossed wiring in the nervous system and nerves linked to pupil constriction, or perhaps blinking too, connect also to the part of the brainstem that registers irritation in the nose, and the need to sneeze, triggering sneezing if the stimulus is sufficiently large.
< Message edited by Number 9 -- Aug.-2th-2008 8:33:25 >
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