An ophthalmological explanation
of REM sleep

The hypothesis:
     The oxygen supply to the cornea is precarious and it needs to respire across both its surfaces in order to maintain its metabolism. For example, cutting off the access to air to the front surface with a contact lens, will lead to swelling and clouding of the tissue. 
     To bring oxygen to the rear surface it is necessary to continually stir the fluid in contact with it, the aqueous humor. With the eye open this is assured by a thermal circulation resulting from the cooling by the corneal surface by the air. 
     When the eye is closed during sleep, on the other hand, this circulation is abolished and the cornea is at risk of suffocation. This is avoided by episodes of REM (rapid eye movement) which stir the aqueous humor. 

  • Text of article in Experimental Eye Research, vol.66, pp139-145 (1998): 
  • Movies of circulation in anterior chamber as result of convection or eye movement may be made available later