Does the Sorcerer's Empower Metamagic influence die rolls for a sleep spell?

Question

This question was inspired by this question about dealing with a creature protected by the Invulnerability spell.

Empower spell reads:

When you roll damage for a spell, you can spend 1 sorcery point to reroll a number of the damage dice up to your Charisma modifier

Sleep says that...

This spell sends creatures into a magical slumber. Roll 5d8: the total is how many hit points of creatures this spell will effect.

In the case of a single creature, the sorcerer is rolling for the sleep effect against the creature's amount of hit points (if one can isolate the targeted creature).

Is the fact that the sleep spell is affecting that creature's hit points equivalent to rolling damage, or is that a stretch too far in finding a creative use for the empower metamagic feat?

Answers that address Rules as Written and/or Rules as Intended and/or Rules as Fun are within the scope of this question.

Answer 1

RAW - No, empower cannot affect the roll in sleep

Each weapon, spell, and harmful monster ability specifies the damage it deals. You roll the damage die or dice, add any modifiers, and apply the damage to your target.

Damage dice, both logically and as indicated by the rules, are only rolled when damage is being determined by some effect.

The sleep spell does not do any damage. The dice, as you point out, are only there to determine "how many hit points of creatures this spell can affect". Therefore, there are no damage dice involved with the spell.

Advice on Houseruling/Rules as Fun

If you are considering allowing this at your table, I have some points to consider. Make sure that you are willing to extend the empower ability to other similar non-damage spell rolls or that you are clear that you are limiting it to just sleep. If you fail to do the latter, the player might assume the former and expect the exception to work for other spells with non-damage rolls.

Just allowing it for sleep does not seem highly problematic, and non-damage spell dice rolls are, to my knowledge, fairly uncommon. So allowing this is unlikely to have dire consequences in your game.

It is worth noting that sleep can be a very powerful spell at low levels in the right situations. So, as a DM allowing this, prepare to have the spell hit more often. This is a spell that can end encounters if used properly (especially single enemy encounters). Of course the same could be said of many spells, but it is something that you should be conscious of.

Answer 2

Yeah, that's beyond a stretch. Hit points and damage are distinct and separate concepts, which means that something that just counts hit points without causing damage isn't damage or a damage roll.

Since sleep causes no damage and involves no damage roll, it can't be affected by the sorcerer's Empower.