Nope. You can sleep them all and use DP without waking them up.
My MA IDs:
Fiend Space: 211464
Well, let´s say it works, but I find it more efficient to arrange the enemies with holds, confusion and fear in nice clusters for Drain Psyche.
Mass Hypnosis is just to situational to have any room in my build and is next to useless in teams as most team members are not too happy when you interrupt their killing spree by telling them to stand back until you had your little pit-stop. (Most of the time you will want to use Drain Psyche in the middle of a battle anyway in which case sleep will do no good either.)
If it has eyes, you can blind it, if it has blood, you can make it bleed, if it has a mouth, you can make it scream.
Whats the endurance recovery like on this power? and how long does it last for?
If I recall correctly it´s something like 100% regeneration and recovery per mob hit (up to 10 mobs) and the effect lasts for 30 seconds.
Basically, if you hit enough mobs you will see your endurance snap back to 100% in a blink regardless which powers you spam (and health will regenerate fast, especially if you slot two heal SOs like me).
If it has eyes, you can blind it, if it has blood, you can make it bleed, if it has a mouth, you can make it scream.
Nice sounds quite good, shame its got a small duration tho 
! So with DP and Health from the fitness pool, you could get some cool Regen for 30 seconds?
So put 3 recharges in it as well and get hasten, ps don't forget the accuracy to 
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Basically, if you hit enough mobs you will see your endurance snap back to 100% in a blink regardless which powers you spam (and health will regenerate fast, especially if you slot two heal SOs like me).
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fast to put it mildly - used it before with about 12 longbow wailing on me my health dropped to about 80% and didn't shift from there - only problem is when it runs out you faceplant instantly with that much aggro on you.
Mind of Gaia lvl 50 Defiant's first Mind/Storm 'troller.
Deadly Doc 50 Dark/Dark Corr
and lots more on Pinnacle,Union and Defiant
Just curious, because I'm thinking of rerolling my plant/thorns (lost the love for it) as a mind/psi, if Mass Hypnosis is used on a Mob does the Drain Psyche power break the sleep? I am thinking from a solo or team view point here.