Welcome to the daily halacha (Jewish law). If one slept on a bed overnight and then noticed that there was food under the bed—a closed bag of chips or a closed Coke bottle—can they have the food? Can they have the drink? Why is this even a question?
We know that the Chachamim (sages), Rav Chaim Palagi, Mishnah Berurah, and Ben Ish Chai all bring this down. There’s something called Ruach HaTumah. Ruach HaTumah is the impure spirit that comes at night. It comes at night because it’s dark, it’s nighttime, and there’s another Ruach HaTumah that comes from sleeping itself. So food that’s under a bed becomes impure.
The halacha sefarim (religious books) bring down that a person should never put any food or drinks under his mattress, under the bed itself, or under his pillow, because then the food becomes assur (forbidden); the food becomes tameh (impure). However, if the bag of chips was fully closed, and the Coke bottle was fully closed, the Chachamim say there’s room to be lenient in our days. Specifically, if the floor under the mattress where the food was placed was carpet, or, let’s say, a wooden floor, that’s another reason why we could be lenient in our days. This follows the Kabbalah (Jewish mysticism) reasons that the koach hatumah (force of impurity) of the ground is only on mud ground or sand ground, but not on the floors we have in our houses, which are made out of wood or carpet. So therefore, halacha l'ma'aseh (in practice), a person should never leave food or drinks under their bed. However, if the food was closed, if the bottle was closed, and it was on top of a carpet or a wooden floor, bediavad (after the fact), they could have the food.