its ascending order of their current HP. Check the wording.

As a DM I've tweaked this for my players. Yes to affect current hitpoints, however, if the remaining total falls to around half or more of the remaining current health of the target, they will be effected by exhaustion temporarily until the spell ends. I never liked how if the total missed the target's current health by a few points and having the spell completely fail.

Would you, as a DM for grins and giggles, house-rule a single viable target receiving the the full HP hit and, if there's enough left over for the max HP beyond 0 (as hypothetical damage, not actual damage), to have something special happen to that one creature—like a coma requiring a Restoration spell or something to undo? My brain is thinking along the lines of HP damage beyond 0 equal to the max HP being instant death even though Sleep is hypothetical damage.

Slep cat

I would argue that sleep is also effective against any group of creatures with a low level of HP. Considering that it's 22.5 HP on average, that's 3 goblins or 1 orc (assuming they're at full HP). At low level, that's about 33% of the monsters at the low end to something as high as 50%. Again it depends on the enemy group and how many are damaged, but sleep is really, REALLY good until about 3rd or 4th level and by 5th it's outlived its usefulness.

I feel like the usefulness of sleep tapers off at around 5th level. Yes it scales, but you have better things you could cast as an area-wide control or disable spell by that point. Like...Hypnotic Pattern or Fear. You could even cast Fireball if you believe you can kill the enemies that you're targeting with it.

The spell says current hit points.

@DNDBeyond Team, could we get a button on this spell to roll the # of d8s applicable to the spells casting level?

Quote from TravisDBarrett >>

I take this to mean that they fall unconscious for one minute, and then start to wake up? or they remain asleep until something gives them a reason to wake up, like damage or jostling?

So if I cast it on a couple goblins, effectively ending combat, so long as they rush to dispatch or restrain the goblins or how would you handle that?

 "each creature affected by this spell falls unconscious until the spell ends, the sleeper takes damage, or someone uses an action to shake or slap the sleeper awake."

The spell would and after 1 minute, causing them to wake up.

I think it’d be hilarious to kill a level 14 zealot barbarian with this spell (if used cunningly).

Quote from Grunch >>

I find this spell works way too seldom as written.  Going forward I'm going to try doubling the dice for the base and higher levels.

If that's  too strong, I may switch the d8's to d12's and add a single die to base and upper levels.

The spell should do the thing it says it does (it should feel magical) and I have never seen it work as intended, even against low level targets.

 It's worked fine for me, put bandits and goblins to sleep and a whole room with centipedes.

So, if an aberrant mind sorcerer were to use this as an action and get 3/5 bandits. Bonus action (metamagic) cast hunger of Hadar on the group. 

3/5 bandits are now prone, blinded, and unarmed when they wake up. 

Is that correct?

Forgot to mention our campaign let's us use multiple spells a turn (such as with haste, or hasten spell) at the cost of exhaustion points. 

Put to sleep tavern and steal a room key for free habitation and write down yourself on the book updating it after recasting every day at a time when not many people are at the tavern.

Mildly unethical but that's not what adventurers do. (as in contemplate ethics.)

Current hit points

BALLS

Current 

one of my FAVORATE Spells

Do constructs have immunity to sleep?

Paragraph 1, Sentence 2:  "current hit points".  It is definitely beneficial to "soften up" target(s) before hand.