The Hills stars, who finished second in Friday's (January 25) final, said that they struggled to sleep because they were unsure what their "mentally insane" housemates were capable of.
Spencer Pratt told the Daily Star Sunday: "We didn't sleep much at all. I always had one eye open. We were watching them thinking they were going to try and kill us in our sleep.
"We were constantly nervous something might happen. Every time we saw any of them near knives we left the kitchen straight away.
"Some of them would itch their own face with a butcher's knife - it was mentally insane. If they'll hold knives by their own faces I didn't know what they were capable of."
Heidi Montag added: "They were at such an intense level in the house, we thought they would come and mess with us. Who knows what they would do?
"At times they were very volatile, easily triggered and they had violent tendencies. I was really scared by Razor's behaviour. I thought we would have to run to get away from it. I didn't want to get into a fight at all costs."
Spencer suggested that the other housemates "hated" them because they "upstaged" everyone else on the show.