Woah.
What had transpired that led up to this?
So, it turned out... you were right all along. Equestria was a real place. How you got here, though... you had absolutely no idea. It seems as if your memory from then up to this point has been nothing but a blank, and you don't know why that is. However, it is not the thing you are focused on right now. All you want right now is rest and recuperation.
You are tired. Like, REALLY tired. If you could describe how you felt... it was like lead weights were attached to your eyelids... your eyes have had their protective outer fluids drained away... your body felt like it was made of lead... you are quite literally about to collapse from exhaustion. Maybe you were foolish enough to pull yet another all-nighter the previous night... whether it was playing video games while binging on potato chips and Mountain Dew, or downing coffee while studying for a test at school, you aren't exactly sure.
In any case, you start looking around to see if there is any place you could comfortably rest for the night. You find some elegant furniture that you try to lay on... but quickly realize it is for aesthetics, not function. They are not properly shaped to lay on. Regardless, you really feel like you need to get some sleep soon. Hell, even the floor looked comfy at this point, more so than the furniture.
At that moment, however, you hear footsteps approaching you from behind. You turn around to see... Princess Luna... your favorite alicorn... the one who taught you that people do respect and revere you, even if they do not show it...
Regardless of your fatigue-reduced awe, Luna stared at you curiously.
"Well now..." she began. "...how did you get in here?"
You merely glance around. Honestly, you can't even think with how worn out you are.
"You are a human, are you not?" Luna said.
You merely look down at your person, examining yourself before lifting your head back up to the alicorn.
"...Not the talkative type, I take it?" Luna asked, tilting her head.
You let out a voiceless sigh, slouching over a bit.
"It is alright." Luna said. "I understand; you are tired. I daresay you look dead on your..." she trails off as she examines your feet. "...well, those aren't hooves."
Finally, someone noticed. Perhaps she could be willing to help you with this problem? As it turned out, she was...
"Come," Luna said. "I can show you to a room where you may rest for the night."
A room, presumably with a bed. Right about now, it sounded like heaven to you, just to lay on a nice mattress and burying yourself under some covers. Princess Luna escorted you to a spare guest bedroom in one of the castle's corridors. It had a very elegant bed with a navy-blue canopy, light blue blanket, and white pillows and sheets. As you merely noticed, you were already wearing your night clothing, as well as barefoot, so getting into the bed immediately was no problem for you. As for how you would be able to contact anyone or get what you would need to sustain yourself until you figure out what happened... no phone... no wallet... meh, you'll figure all that out in the morning.
Once you were under the covers, Luna generously tucked you in, seeing that you were too tired to do it yourself. As you laid, waiting for her to put the candlelight out... she merely stood next to the bed, hovering right over you.
"Before you allow yourself to drift off to a peaceful slumber..." Luna began, smiling at you. "...would you like to hear a bedtime story?"
At first, despite your fatigue, you are confused. The Princess notices your facial expression that relays this to her.
"Don't worry; it's not any sort of sappy fairy tale, no. It is literally a story about your bedtime." Luna said.
You become somewhat intrigued by what she has to tell you, so you nod to convey that you wish to hear this "bedtime story."
Luna sat down right next to the bed, leaning slightly closer to you.
"Now, here it is..." she began. "...consciousness is merely something that occurs in increments. In all essence, it is something that your brain creates when you wake up. This is something that I have studied and made into a plausible theory over the course of my dream duties. To put it into context that you will probably understand... you know when you use a computer, how you open up, say, a program called 'Notepad.exe'? Well, when you run that program, the program will only remain open in that one 'instance.' When that instance is closed, it is gone forever.
"Now, the program, 'Notepad.exe' is still on the hard memory drive of the computer, but the one instance itself is gone forever. It is gone, and shall never exist again, no matter how many times the program is re-opened. It has been permanently destroyed by closing the program. So, in addition to this, you can save a '.text file' to the hard drive in order to retain any information you put into the program, yet the instance where it was created is gone. However, when you open the saved .text file, the memory is still there, but it is in a new instance, which is reading off the memory imprinted on the computer's drive. It is not the old instance; it is reading it in a new instance from the memory created by the old one. Are you following what I am saying so far?"
Slowly, and somewhat reluctantly, you nod at Luna. Smiling a bit at your apparent understanding, she continued.
"Alright, so... your brain, for every time you awaken, creates an 'instance' of your 'consciousness program,' and when you fall asleep, that instance of your consciousness is destroyed. It is gone forever, and you effectively cease to exist... you are gone... permanently. That one instance of you shall never exist ever again. It is dead... forever. So, every time you wake up, it is a brand-new 'you' that is created, utilizing the memories of the prior instances of your consciousness, because the 'old you,' the one the existed the day before... is dead. Gone, forever."
This revelation surprises you. You had never thought of sleep being like that before... but it doesn't really impact your way of thinking all that much, since you are too sleepy to really let it sink in all that much.
"You merely carry on the illusion of persisting due to the new instance, or new life of you reading off of the memories imprinted in your brain from your old lives. You feel as if you are but a single consciousness carrying on every day since you were born... but that is not the case at all. Your body is simply a biological shell, a vessel, that has served as the 'habitat' of thousands of different consciousnesses, all of which have been created as you awaken, and destroyed when you feel asleep.
"To put it quite simply... you are born every morning, and you die every night. So, that means... nearly everypony in Equestria, but a few hours ago on average, has died forever. However, in less than eight hours from now... they will all be born again, thinking they are still their old life. As I said before, it is an illusion, because the new consciousness has access to all old memories, just like a Notepad.exe program opening previously-written .text files from prior instances."
This was making your brain spin from thinking about it. It was even putting you somewhat on edge. To think... going to bed is basically a death sentence... but at the same time, something about it all felt very... relieving. Like having a chance to start over every day... and from how tired you felt, in other words... dying... it seemed like just what you needed.
"So..." Luna began. "...in all essence, you shall never see me again, nor shall I see you. Because, in mere moments from now... you will die. And shortly after, I shall die as well... but you'll have the pleasure in knowing that a new you, with previous memories of your old lives, will carry on to see me tomorrow... just as the same will happen with me."
Very slowly... your eyelids slowly begin to cover your vision. You try to open them again... but it is very difficult to do so. You simply cannot stay awake any longer. Slowly blinking, you continue to look at Luna, who takes notice of your weariness.
"Do not fight death, my dear..." she said, gently rubbing your head with her hoof. "...just let it take you from this world..."
Finally, your eyes close, and immediately... you feel yourself slipping into the dark, silent, but comforting embrace of death... and you feel absolutely safe knowing that it is all over... and that you shall be reborn the moment you wake up in the morning, and a new you shall carry on in your old, but refreshed, body, with the previous memories of all your old lives...