Heard from a coleague -so again, myth or history?- that a couple of years ago at maastricht airport the same thing happened. Allegedly there should have been 2 atco's but, due to the fact that there was only one flight early in the morning and then nothing to do till l8r, the guys decided one of them could sleep a bit longer and join after a while. So, only one guy left to man the tower for the first flight. He was there on time, opened the tower, the flight gets a bit delayed, the guy is tired, the guy falls asleep in his position...a/c arrives and calls in....nothing...calls in again....nothing nothing. Eventually, about 20 mins later, the second guy comes in and finds out what's up and the a/c lands.
Funny thing is, next day and about 10 min after the tower opening time, one controller from the muac gets the mike and goes on guard "wake up! wake up!" while making ring an alarm clock...