Can a wizard use the Sleep spell to hunt for food?

Question

In the description of the Sleep spell (PHB p276):

This spell sends creatures into a magical slumber. Roll 5d8; the total is how many hit points of creatures this spell can affect. Creatures within 20 feet of a point you choose within range are affected in ascending order of their current hit points

Assuming the Wizard is alone, without proficiency in Survival (and even a -1 to WIS), but still wants/needs to eat something while lost in the jungle and not able to hunt properly. Is there any reason not to allow a wizard to find food by launching this spell in a rather luxuriant environment with supposedly a lot of game (i.e. jungle), or on a river?

Answer 1

Yes!

This will definitely work! Sleep does not have any requirement for you to see the creatures, so as long as there are creatures in range, then the spell will work as advertised.

However, you will still need to find these animals that are now sleeping and potentially out of your visual awareness and will need to work with your DM (or your players) on how discovering the sleeping creatures will work.

And then you still have to kill them.

Answer 2

I'm assuming you mean "Wizard casts Sleep, mauls any sleeping creatures, then eats them" as a short-cut for the normal way of foraging for food? If that's what you mean, there's plenty of reasons why this wouldn't work out well. And also some for why it would.

The normal act of foraging for sustenance from living creatures depends on a few different things. Generally speaking, the DM would ask you to make a Wisdom(Survival) ability check, which essentially covers all of these:

• You need to find them (a random 20ft radius (40ft diameter) sphere of jungle is unlikely to contain much). Also, line of effect rules (see @gszavae's answer) limit what creatures in the area can actually be affected; being behind a tree trunk from the chosen point would block it.
• You need to get close enough to them (once you pick up a deer's track, you still need to get within 90ft of it. Prey animals are flighty and will run if you're not careful.)
• You need to be fast enough to catch it off-guard (even if you're quietly closing in, casting Sleep requires motion and sound which will alert the critter)
• You need to make sure you can actually eat them (that brightly colored frog might be sleeping, but that doesn't mean it's safe to touch)
• You need to know how to skin and prepare it so as not to waste too much or choke on the bones

Sleep will help you with none of these things. Sleep will help you quickly put a creature to sleep, so it can help with getting sustenance, but it cannot replace looking for food.

So what does Sleep do?

If it were me as a DM and you suggested this, I'd tell that being willing to cast Sleep as part of your attempts to forage for food would totally give you Advantage on that Wisdom(Survival) check, but that's all.

(Unless the adventure revolved so much around getting food that a single check wasn't enough. In that case, you'd be making a bunch of skill checks and choices in your quest for food, but if you got to the point where you're close to prey and in a position to cast Sleep, yeah, that animal would fall asleep)

Answer 3

When trying this, beware line of effect

A lush jungle filled with bushes, trees, rocks, logs, crevices, hills, and gullies may seem like the ideal place to cast this spell. However, you need to keep in mind that you must have an unobstructed line between yourself and the target point:

To target something, you must have a clear path to it, so it can't be behind total cover. If you place an area of effect at a point that you can’t see and an obstruction, such as a wall, is between you and that point, the point of Origin comes into being on the near side of that obstruction.

And the spell only affects an area that has an unobstructed line to the target point:

A spell’s effect expands in straight lines from the point of Origin. If no unblocked straight line extends from the point of Origin to a location within the area of effect, that location isn’t included in the spell’s area. To block one of these imaginary lines, an obstruction must provide total cover.

This may make it difficult for any creature to be affected by the spell. For example, a bird on the other side of a tree, a deer behind thick scrub, or rabbit in a burrow would not be affected.