HaLeiVi said: “oy vey, there’s a big difference between falling asleep and going to sleep. With the first you are Yotze Ad Delo Yada, with the latter you aren’t.”
The Ramo says “veyoshein.” I don’t know if that means going to sleep or falling asleep, but I do know that the Beis “HaLeiVi” was noheg to actually force himself to go to sleep.