7:50 AM PT -- Simon actually fell backwards down the stairs. We're told he had already gone to the kitchen, and was on his way back upstairs when he fainted and tumbled.

Simon Cowell was rushed to a hospital early Friday morning after falling down a flight of stairs.

We're told Simon was asleep in the upstairs bedroom of his London home. He woke up in the middle of the night, felt dizzy as he tried to go downstairs to the kitchen for some milk. We're told he fainted and tumbled to the bottom of the staircase.

An ambulance came, put him in a neck brace and neighbors saw Cowell placed in the back of the ambulance on a stretcher.

We're told doctors have performed a CAT scan and more tests are being performed.

He's in stable condition and still in the hospital.

Simon's girlfriend/baby mama Lauren Silverman was in New York visiting her son and is currently on a plane flying back to London to be with Simon.