This is just from my experiences at the Sanatorium. If some is on the guide page, it's probably because I also think it's useful. By the way, I play on mobile. So if this does not suit PC Users, I'm sorry.
How to Get to the Sanatorium[]
First, I'd recommend looking at the map while it loads. When you first spawn in, there's a chance the walls might be glitched and you can see if it's day or night. If it's night, switch on your candle and cross your fingers. On the occasion, there may be a spider who has decided to stay here for the whole time. If there's a spider, it's recommended to leave and find a new server unless you're:
A. A nurse
B. A person who knows how to deal with spiders
C. Stubborn
When meeting a spider at the spawn, do not provoke. Try to hide behind a stalagmite, and stay out of its field of vision. If it sees you, it will kill you. If you're seriously desperate to get out of there, use mobile to check in front of the stalagmite. Hopefully the spider's AFK/distracted. Then use the sprint button(the button that looks like someone running) and run on out of there. If they're guarding the door(highly unlikely but could happen), you can wait until day, take your chances or rejoin.
There, exit the cave and if there's a melon, take it. It's good for you.