It depends on two things, 1st are you a patient or care giver and 2nd hospital rules concerning care givers.
My husband had ALS, so we spent quite a bit of time in various hospitals and they had different rules and setups. From small town and big city hospitals, large training hospials, and the regional VA hospitals.
As a patient just about everything is provided, remember to bring power cords and adapters for electronics, a book to read and a small notebook and pens. Also, a 6’ extension cord could be helpful. Some new beds have outlets, but old ones don’t. A travel pouch with small toiletries because they can and do run out of supplies.
As a caregiver it depends on the hospital. For food, some will provide meals, some don’t. Most hospitals have cafeterias, but the cost can add up if it’s a long stay. One of our hospitals only cooks for the patients on the weekends, so having a few microwaveable meals, energy bars, and snack cups is a must. Have water flavor packets because plain water gets old real quick, sodas will get expensive and the coffee is usually “cooked”. Instant coffee and tea bags are also helpful. Don’t count on vending machines they are usually empty on weekends. If you like to make your own dry soup mixes, it will cut down on the weight, but make sure to bring a microwaveable cup and utensils.
For sleeping arrangements it varied. One ICU only had cardiac chairs, which was equivalent to sleeping on concrete. Slept in Ted’s power chair, I’m a side sleeper and it couldn’t lay flat. Started carrying a cot and you can usually talk the nurses into giving you a blanket and a pillow. However, some head nurses may not let the cot in the room as it may impede their movements. Some had nice couches ( loved those).
For clothing I kept a couple light weight T-shirt’s, a pair sweat pants and undergarments. Something that I could hand wash and it could dry quickly if need be. A jacket is a must and favorite house shoes for comfort.
Same toiletry bag, electronic supplies, reading and writing materials. And don’t forget the extension cord.
Cash, don’t forget cash. Include quarters and small denomination bills just in case those vending machines are full. 😉
Hope this helps.