I slept for like 4 hrs in ICN. They have a transit lounge and at night there are often people all over the area sleeping. All the couches were gone (I landed at 3am) and woke up about 7 with all my stuff still in place. I slept, literally, behind a couch that some israeli dude was sleeping on (we later had lunch at the airport and chatted). Wasn't bad.. like a 4th grade sleepover.