For Albert and Patty Watson, it was a rude awakening. The clatter of breaking glass and falling metal and bricks is not a sound they usually hear in the middle of the night in the middle of their home. When they went to investigate, they found something even more unusual: a car in the family room.

The Watsons, who have lived in the house on Sportsman Drive in the Falls Church area for 18 years, were not hurt when a 1976 Pontiac Grand Prix crashed into their home at 11:30 Saturday night. Nor was their 180-pound Great Dane. The 25-by-13-foot family room and most of its furnishings were destroyed, said Patty Watson. She estimated the losses at $40,000, including antique crystal containers and a rocking chair that was more than 100 years old.

The Watsons were asleep in a bedroom that adjoins the family room when the crash occurred. Patty Watson said she "bounced out of bed and ran into the family room. I tried to turn on the lights, but couldn't. My husband came in after me, and I turned around to him, and said, 'There's a car in our family room.' "

A young man, whom she described as about 25 years old, was still in the driver's seat. They asked him if he was hurt, Patty Watson said, but he did not answer, and ran away.

Neighbors speculated that the driver may have been leaving a party at a nearby house.

Fairfax County police said yesterday they did not know the driver's identity, but the car was traced to a neighborhood resident who is on vacation in Florida.

Patty Watson said the car ran off a cul-de-sac, down a six-foot embankment, into the back yard, and then through the glass doors into the family room.

The Watsons had left the room about a half hour before the crash. Patty Watson said they had decided to go to sleep earlier than usual, a decision she said may have saved their lives.

"I had left my watch on the chair I sit in and we can't even find that. The good Lord must have been looking over us or we wouldn't be here," she said.

By yesterday afternoon, the car had been towed away and Patty Watson was picking up the pieces and joking about the incident. "It's not everyday that you wake up with a car in your family room. I sure know how to throw a party, even when I'm asleep," she said, adding that "if you lose your sense of humor, you lose everything."