- "I must be more tired than I thought..."
- — Mii, Tomodachi Life
Sleep occurs when a Mii is either taking a nap or sleeping for the night. When in the Mii's apartment when sleeping, a lullaby version of the apartment music will play.
At night, Miis are in their bed wearing Pajamas and, unlike naps, are in a deep sleep and cannot wake up. When they're sleeping at their house for the night, the player cannot call them, due to their deep, deep sleep. The player can draw on their face, or press the clear button to erase their face, leaving it blank (excluding the nose). The drawing applies only to the interference itself, and is not permanent on the mii.
The player can also view Mii's dreams. A thought bubble with a dream picture on it will appear. Clicking it will show the dream. When the dream is over, the Mii will wake up. If he/she is sleeping for the night, they will wake up, comment on their dream, and go back to sleep. If the player taps "Edit Mii" and changes the Mii's personality, they will wake up until the player leaves the apartment. They will often talk in their sleep.
Things the Mii might say in their sleep
"<Mii> in the kitchen, <Mii> in the living room, <Mii> on the coffee table, <Mii> is taking over!"
"<Mii> stole all of my <food/treasure>!"
"A pool full of golden <food/treasure>? I'm going to go for a golden swim!"
"Amazing! Incredible! Unbelievable!"
"Another encore? Well, if my beautiful audience insists!"
"Are you trying to pick a fight with me? Careful what you wish for!"
"Pick on someone your own size! Wait, no, stop! I'm definitely not your size!"
"But the ceiling is too low for jumping jacks."
"Do a barrel roll!"
"Does anyone need a meerkat? I have an extra."
"Don't open that! You'll destroy us all!"
"Don't worry about me, I'll be fine. Dry those tears, Mr. Bear."
"Ha ha ha! Ha ha ha ha ha! I don't get it."
"Ha ha ha! Stop laughing! Ha ha ha ha ha!"
"How did I lose? I don't get it."
"I can see it from here, it's beautiful."
"I can't decide, I love you both!"
"I don't think that's supposed to be flammable..."
"I love you, my darling! Hee hee hee!"
"I need compliments, so many compliments!"
"I need it right away! Tomorrow it'll be too late!"
"I won one million dollars? This is a dream come true! I'm gonna buy an ice cream truck!"
"I'll pay you back with interest! You can totally trust me..."
"I'll save you, islanders! Quickly, to the <Mii> cave!"
"I'm going to take over the world, starting tomorrow!"
"I'm trapped! Where's the exit!? Oh, it's by the popcorn stand."
"I'm not scared! I'm really not scared!"
"I'm so late! Maybe they won't notice...."
"If you agree with me, raise your hand. So, nobody then? Oh."
"It's okay, you tried your best."
"It's so soft, so luxurious..."
"My cover's blown! Abort, abort! Wait... Nevermind..."
"It's dangerous to go alone! Take this!"
"It's <Mii>'s fault, not mine!"
"It's time to get serious! No, seriously!"
"Just 5 more minutes!"
"May I have this dance? Hee hee hee!"
"<Mii> stole all of my <food/treasure>!"
"My mommy! Mama-mia!"
"My name's <Mii>. I'm your boss from now on, so shape up."
"Not here. Everyone will see us. I need privacy to thumb wrestle."
"Officer! Stop that doughnut! It's really a secret agent in disguise!"
"Officer! Don't let that doughnut get away! It's a secret agent in disguise!"
"Remember to look both ways before crossing your fingers."
"Put the artichoke down, Billy boy! Put it down!"
"Stop that, pizza thief!"
"Stay back, pizza thief! Stay back, I say!"
"Take me to the keyman!"
"The train will be here any minute. I guess this is goodbye."
"This is all for me? There must be a catch."
"This is my island now! MY island!"
"This is real life? So the island was just a dream!"
"This sandwich doesn't look like the one from the commercial!"
"Want me to cook this up for you? I can cook it up real good."
"Whatever happened with the you-know-what? Don't play dumb!"
"Why am I the only one here? And why am I in my underwear? I should go."
"Why are you having [a/an/some] [Food], <Mii>? ... Oh, I see."
"Why do bananas have their own packaging? It's a mystery..."
"You think you've got it rough? Try walk in MY shoes, Mr. Eggplant."
"Wow! I can't believe it! So many monkeys!"
"You saved my life! I owe you a soda!"
"You want me to be [Island name]'s new president? I don't know what to say!"
"You're my father?! No! Actually, that's kinda cool..."
"You're not my mommy!"
"You're right—I've been hiding something all along. I'm actually Super Dude/Gal..."
- Sometimes, in their sleep, a Mii will say "It's dangerous to go alone. Take this". This is a reference to the famous line in the Legend of Zelda.
- Do a barrel roll is also a reference. This time, referring to Star Fox.
- "You're my father?! Nooooo! Actually, that's kinda cool..." Is a reference to Star Wars: Episode V – The Empire Strikes Back
- When married couples sleep at home, The male mii wears blue pajamas, while the female wears pink pajamas.
- "I'll save you, islanders! Quickly, to the <Mii> cave" and "Survey says" are references to Batman and Family Fued respectivley.