At the end of a dream, 2 different kinds of numbers can appear. There is always a green one and sometimes there's a red one.

The green number displays what dream you just had. Whenever you have the same dreamsign. You'll get the same number when waking up.

Red numbers. These numbers are more rare and also dreamsigns though these can be missed or hard to find, they are optional but can help in waking up. (but also sometimes hinder it)

Knowing these numbers actually has an use in-game. There is a screen in the top right corner of the map that has a chance of displaying your current lucid dream number (with a 20% failure rate). Knowing this can instantly make the dreamsign obvious.

Here's an image of the entire house showing what rooms I'll be talking about.

Below are all green numbers that I know of, and what their dreamsign is. Suggestions to what any unknown numbers are would be helpful.

0: Reality. Nothing wrong with the world. Stay alive until the timer hits 0 to win.
1: Kir slowly slowly moves left, up, down and moonwalks.
2: Kir shoots in random directions.
3: Kir leaves behind his legs when walking.
4: Several passive undead are scattered around the house to tell you a story.
5: A tree replaces the table in the living room.
6: All objects are transparent.
7: There are much more enemies to the point where it is very hard to even get to the end of the timer. There's at least 2 enemies after every door.
8: Enemies are super fast. (scary)
9: Enemies not meant for Jackie or Victor are invulnerable. (so, most of them)
11: Zombie news on a TV screen in the house.
12: There is a Kir copy in bedroom.
13: Kir is placed behind all of the objects in the game.
14: Objects disappear visually after interacting with them.
15: Invisible wall in the science room locks off the right part of the room.
16: An eye randomly appears in the washing machine in the bathroom.
17: Someone is standing in the engine room.
18: Someone is sitting on the chair in the bedroom
19: A skull randomly appears in the microwave in the kitchen.
20: Someone is in the science room.
21: Someone is in the kitchen.
22: Something is in the bathroom.
23: Someone is standing in the living room.
24: Someone is in the game room.
25: Someone is on the bed in the bedroom.
26: Someone is in the science room.
27: Someone is sitting in the secret room.
28: Someone is on the couch in the living room.
29: Someone is in the hallway next to the kitchen.
30: No enemies spawn at all. Parasite talks to you in the secret room.
31: Someone is in the kitchen.
100: Clock in the living room spins rapidly.
101: Kir's bullets go right through enemies.
102: Disco rainbow light replaces a regular light source in the house.
103: Phone call in the living room with the parasite talking to you.
106: Kir talks in a different language.
107: Items (ammo, meds, glowsticks etc) picked up are not added to your collection. (they also make no sound when picked up)
108: Same effects as 107 but Kir starts with no ammo and your crew give no ammo to you. (enemies can kill you)
109: Magic rainbow land in a window in the bedroom or secret room.
110: Enemies move through walls. (scary)
112: shooting makes duck sounds on impact. (game sound on)
113: Knock harder text appears on a wall in the hallway.
114: Enemies die in 1 hit.
115: Kir's icon during dialog is a zombie.
116: Kir's shadow grows to giant proportions over time.
117: Enemies have no parasites on their heads.
118: Fuse box in the closet is fixed by default.
119: Bottom lamp in the bedroom is not broken.
120: Meds deal 10 damage instead of healing 20.
121: Victor loses more and more of his mustache, the more you talk to him.
122: Shells from shooting float in the air and disappear.
123: All characters on the picture in the bedroom have the same head. (with no eyes)
124: There is a hedgehog in the starting hallway.
125: Kir has no eyes during dialog.
126: Picture in the bedroom has Chthulhu in the background.
127: Freddy Kruger emerges in the picture in the science room.
128: Candles are put out over time by shadowy hands.
129: A wall is missing in the engine room near Victor.
130: The phone in the living room is gone but is still ringing.
160: Start in a small room with no ammo. A phone reveals the hiding spot for a bullet.
161: Start in a large empty room with tons of ammo. Enemies and shooting yourself heals you. Meds deal 10 damage.
162: Start in large empty room with no ammo. Lights turn from red to green depending on how close you are to an invisible desk with a bullet.
163: Start in large maze with no ammo. Many wardrobes with candles on them are scattered about. One contains a bullet.
200: Real Indian elephant item hidden in the house.
201: Spanish karabama item hidden in the house.
202: Immortality pills hidden around the house.
203: Pen item hidden in the house embossed with "Parasite, Kir rise and shine".
204: Bottle of lava item hidden in house.
205: Bill hidden around the house mentioning "Sterilization of vampires and werewolves".
206: Music disc hidden around the house with info about parasite.
207: dove item hidden around the house which is a friend turned into a dove.
208: There's an item in the fridge with production date 200 years in future.
300: You have near 1000 batteries for the flashlight.
309: Ammo for the currently selected gun drains over time.
311: Blood is green.
312: All Fuse boxes around the house are missing, except for the broken one in the closet.
313: Doors vanish when opened.
314: Looted items infinitely reappear in containers.
315: The phone and lamp in the living room traded spots.
316: Kir confuses pistol bullets for shotgun shells when they are picked up.
317: The arm below the blueprint in science room vanishes when the blueprint is moved.
318: Ice cubes are found outside of the fridge.
319: The font of Kir's watch in the top left corner is different.
320: There's teeth in cracks in the walls around the house.
321: Bloodstained scientist portrait with broken glasses replaces the usual self-portrait in the house.
352: Your guns hold double the max ammo.
399: Leprechaun tells you that this is a dream in the previous cutscene. (mean)
400: zombie corpses vanish over time while offscreen.
401: Doors close behind you.
402: Ammo instantly refills when reloading.
403: Self portrait painting replaced with Kir's head.
404: Kir looks like a parasite zombie in the mirror.
405: Flashlight has rainbow light.
407: Candle flame is huge.
408: Inventories don't have an opening animation when interacting with them.
409: Objects have random inventory names when interacted.
410: Glowsticks follow you when dropped down. (Spooky)
411: Phone call in living room says that treasure is hidden in your brain.
412: Chair in bedroom vanishes when not looking at it and reappears when looking at it.
413: Stool in bedroom jiggles when Kir is not looking.
414: No one has shadows.
416: Candle flame is invisible.
417: Glowsticks fall through the world when used.
418: Locked door in the starting hallway is missing.
419: There's a invisible light source next to the wall in the engine room.
420: Note in living room mentions one person brought the angel statue in the house. Computer in science room mentions that another person brought in the same statue.
421: Note in living room is wife talking about dead husband. Computer in science room has a message about said husband talking about dead wife.
422: Note in living room mentions either barring or installing steel shutters while the the windows are barricaded the other way.
423: Dead person under the blueprints has the same face as the self portrait in the house. Living room note says they're a stranger.
424: Dead person under the blueprints has the same face as on the photos in the house. Living room note says they're a stranger.
425: The note in the living room mentions portraits of century old scientists being hung up in the house. Photo of same person with the wife can be found in the house in the bedroom or science room.
426: Newspaper talks about dead scientist from 55 years ago which is present in the house.

427: Newspaper talks about dead scientist from car crash which is present in the house.
428: Note in living room mentions hanging up picture of wife's brother, Same brother is revealed as dead before the note was written in the newspaper.
500: Credit card hidden in house issued 100 years in the past. (around 1900)
501: Watch hidden around the house where Kir says it stopped at 27.
502: Flash drive hidden around the house with 57GB storage.
503: Deodorant in the house with expiration month past 12 or day past 31. (format is dd-mm-yyyy)
504: Book hidden around the house with the word "thousand" after its amount of pages.
599: Pot of gold hidden around the house. Immediately progress to the next dream when its picked up (leprechaun gains rainbow for rest of the game if picked up).
600: jumping parasite enemies don't vanish when defeated. This includes the one that falls off your face at the start of a dream.
601: The TV screen in the science room is on while it's not plugged into a socket.
602: a table in the house has a part missing, causing the upper part of the table to float.
605: Hanging wolf head in main hall has glowing red eyes. (scary)
606: The computer in the science or secret room is on but not plugged in a socket.
607: A carpet in the house changes colors over time in a rainbow pattern.
609: The plant in the bedroom starts wiggling when not near it.
610: Leprechaun is inside the candle/eye painting.
611: There are 2 dove brooches present in the house while the note in the living room says that it's one of a kind.
612: Same dead scientist is present in house twice. Once in the secret room, once in the science room.
613: Same as 612
^ The game actually messed up here. If you lose on this dream, you'll get a hint indicating that the secret room should contain a box with a shotgun that does not have the visual of the shotgun sticking out of the box.
616: Mirror shows you wielding a shotgun always or a pistol if you're holding a shotgun.
617: Shooting the shotgun drops bullet casings on the ground and shooting the pistol/machine gun drops shotgun casings.
618: Eye painting in house follows Kir's movements.
619: Box in secret room shows shotgun hanging outside it which doesn't vanish when box is emptied OR box shows a shotgun hanging outside while not having a shotgun inside. It vanishes when box is emptied.
620: All cracks and tears in the walls around the house are gone.
700: Notes and screen in the science room talk about Kir's dream loop count.
701: The generator is not moving but still makes sounds as if running.
703: Jackie is a duck.
704: Jackie's hair is brown instead of blonde.
705: Victor doesn't know who Jackie is at all.
706: Bearskin in living room has human head.
707: Bathtub in the bathroom has creepy legs.
708: Knock harder text fades into view on the bathroom mirror glass.
709: The corpse in the science room is visible under the blueprint, but moving the blueprint reveals just an arm.
710: Jackie and Victor mention you by a different name every time.
711: Water dripping down in bathroom is invisible. Still makes splash and noise.
712: Victor and Jackie don't have a shooting animation but still fire at enemies.
713: Kir uses the same sprite for looking left and right but right is flipped. The hand holding your pistol is always fully visible.
714: The man in the house has two mothers. (one mentioned by note, other by gifted watch?) (unsure about this one)
715: Kir's reflection in the mirror is flipped sideways.
716: There's a second Jackie standing near the original Jackie in a dark corner.
717: Note in living room mentions husband doing something on a certain date. Newspaper says said man died in a car crash on an earlier date.
718: Note in living room has writing date that is after the death of the person writing the letter. Death date found on science room computer.
800: Victor messes up Jackie's gender. (Victor may not mention a gender at all?)
801: Jackie changes appearance. Whenever you speak to him/her. OR Victor mentions Jackie as "bearded man" while he/she has no beard.
802: Something is in the closet.
803: Someone is in the bathroom.
804: Someone else is in the bathroom.
805: Someone is in the science room.
900: Victor says he knows Jackie for a long time. Jackie says he/she only knows Victor for a couple months.
901: Victor says Jackie wants to grow a mustache like him. Jackie doesn't remember Victor well. (It doesn't really add up but this IS the dream hint)
902: Victor says he and Jackie are married. Jackie says that they could have been married or barely knows Victor.
903: Victor says he hates Jackie's beard. Jackie doesn't remember Victor well. (It doesn't really add up but this IS the dream hint)
904: Victor says that he and Jackie were together before Kir joined. Jackie says they and Kir were together when Victor joined. OR Victor says Jackie has a beard while Jackie barely remembers Kir's name.
905: Victor says he knows Jackie for a long time. Jackie tells you he/she knows him for a couple months.
906: Jackie said you don't know him/her well. Victor says you do know Jackie well.
907: Victor says he hates Jackie's specs. Jackie says that they went to the same class and are good friends.
908: Victor says He and Jackie have a somewhat large age difference. Jackie says they studied in the same class.
909: Jackie and victor both think you were with them when you picked up the other person.

As a finishing note for the green numbers, I wanna explain a bit more about numbers 900-909 as some of them can be very confusing.
If Victor says "Ha! The lad seriously tries to look like me. Did you notice? He's even grown mustache like mine recently!" and Jackie says "Victor! This is it! I just can't recall his name... yeah, it seems he was not a bad man! You are Kir, aren't you?" then this IS the dreamsign for number 901
If Victor says "It's good that you've joined us! Cause this bearded man began to irritate me slightly after a couple weeks that we had spent together..." and Jackie says "Well... we are good friends with him. Once we studied in the same class. Not many people manage to carry on the friendship for so many years, you know." then this is NOT a dreamsign. If Jackie instead says "Victor! This is it! I just can't recall his name... yeah, it seems he was not a bad man! You are Kir, aren't you?" then it IS a dreamsign for number 903
If Victor says "I'm not sure it was the right thing to pick up Jackie. I got no idea how she managed to survive without us." and Jackie says "You know my opinion about him... We could have been a good couple if all that stuff never happened. But he's not aware of my feelings and it's for the better." then it is NOT a dreamsign

Red numbers are generally very difficult to find. They appear sometimes along with a regular number. The science room does not show them at all and their effects are often very hard to notice. More often than not you'll notice a red number after a dream without ever seeing its effects.

Here is a video explaining all red number effects. They are also written down below.

1: Using medkits doesn't deplete them. Flashlight batteries don't drain.
2: All objects around the house (mirrors, fuseboxes, lamps, etc) can't be damaged by shooting at them. Though they still make noise when shot.
3: Kir takes no damage from enemies.
5: Kir moves significantly slower while an enemy walks towards him.
6: An enemy drops an ID card with the parasite on it.
8: Repairing the broken fusebox in the closet visually turns it into an opened medkit.
11: Jackie, victor and the scientist reload their gun instantly.
12: Kir takes no damage at all and starts with full hp.
13: A second Kir leans out from the wardrobe in the bedroom if opened.
14: Creepy eyes appear from under the shelf in the closet.
15: The parasite next to kir at the start is missing.
16: Kir starts with the lighter.
17: Kir starts with 1-4 pain meds.
18: Kir starts with the flashlight.
19: Kir Starts 110-140 pistol bullets.
20: Kir Starts with the crate key or secret room key.
21: Kir starts with 1-4 glowsticks.
22: Kir starts with the shotgun.
60: There are playing cards hidden around the house that have their black and red colors swapped.
69: The Man portrait faces left by default but is shown facing right when interacted with.
73: Rick and Morty conversation textboxes in the bottom left corner of the game room.
279: Reloading the pistol or uzi removes a bullet from your total.
423: There is a credit card hidden around the house where the last name matches that of a stranger in the house.
430: Kir starts with full HP.
441: The angel statue changes appearance if you shoot the fusebox next to it. Dialog when interacting changes too.
442: The photo in the bedroom or science room changes appearance when you look at it multiple times.
501: There is a watch hidden around the house where Kir says it stopped at a different number than what it actually stopped at.
502: Kir explains the flash drive in the house as having a different amount of storage as what is shown on the drive.
503: Dice hidden around the house with 7 pips on a side.
504: Dice hidden around the house with 2 pips on all sides.
547: There's a set of cards hidden around the house where the 9 is not flipped on the bottom side.
548: There's a set of cards hidden around the house where the 4 of hearts has 6 hearts on it.
604: Kir's pistol will fail to shoot if he tries to shoot himself.
608: The rug in the engine room changes pattern every time you close and open the door to the engine room.
615: Kir's walking sounds can't be changed by walking over carpets or corpses.
618: The note in the living room is written in a different font.
619: The newspaper in the kitchen says DIE KIR
632: The poster in Engine room reveals infinite more posters when flipped over.
636: A cartoon-style zombie appears in the engine room and quickly heads down through the wall to the right of the engine.
637: Victor becomes extremely mad when you ask for ammo. And then gives you 20 bullets.
642: A credit card hidden in house which is issued after the parasite attack from which the date can be found in the note in the living room.
709: There is a person under the blueprint in the science room but interacting with it turns it into the mannequin arm.
716: There is a second Jackie hidden in the bottom right corner of the game room.