what causes that?
Must be either the wind, the freezing air, or the light out side the window. I do not know the symptoms, but most people sneeze as soon as they get out of the house/ building after being in side it for a long time specially when the room has no windows and only counting or Air con. The sun light disturb our eye sight as well, and cause us sneeze...
he phenomenon is called the "photic sneeze reflex". It does not occur in all people. The reasons behind the phenomenon are poorly understood.
If you stare at the sun, your retinas would burn and you'd become blind. You're body protects your eyes by sneezing-the sneezing forces your eyes closed.
Because after sleeping you may have dust in your room and therefor up your nose, also looking at light makes you sneeze ^-^