As a postscript to yesterday's post about hostile M-Us in the Dungeon, I'll point out that the Sleep spell in the LBBs, Greyhawk and Holmes Basic is nowhere indicated as being any different than ordinary sleep. This was pointed out in an OD&D Discussion thread by aldarron (Dan B.), and waysoftheearth suggested that any loud noise, like continued combat with unaffected foes, could wake all affected parties in one or more rounds. Later editions, including AD&D and Moldvay, specify that the sleeper(s) must be awoken by another person, not just noise. This rule is now often ported back when playing earlier editions, but it's not in the rules as originally written. However, the comments of Mike Mornard (Gronan) in the same thread make me think that it was always played in Gygax/Arneson games as being a magical sleep. So I don't think there was an intentional change to Sleep to make it more powerful like there was with Magic Missile (changing it from requiring a to-hit roll to an autohit), just a clarification of what was assumed. So it doesn't appear a change in the Sleep spell was the reason for the lesser chance of hostile M-Us in the dungeon in AD&D and B/X.