Asleep (FuraSleep in the game files) is a status condition in the Super Smash Bros. series that is inflicted by attacks with the sleep effect. It has appeared in every Super Smash Bros. game. A fighter that is asleep is shown visibly sleeping.
Any fighter on the ground hit by an attack with a sleep effect will be put to sleep; fighters in the air, hanging from an edge or on a ladder cannot fall asleep (with the exception of Hero's Snooze). Examples of attacks with the sleep effect are Jigglypuff's Sing, Peach's Peach Blossom, Hero's Snooze, and the Poké Ball Pokémon Togepi's Sleep Powder.
In Super Smash Bros. for Wii U's Smash Tour, the tour item Darkrai causes an opponent to be asleep at the start of the battle. In Super Smash Bros. Ultimate, the slumber floor Spirit Battle condition causes a stage's floor to put players (but not Puppet Fighters) who stand on it to sleep.
A sleeping fighter is unable to take any actions until the status wears off.
The amount of time a character remains asleep is dependent on that character's damage percentage. In the original Super Smash Bros., characters sleep longer at lower damages, having the shortest possible duration when damage is 300% or greater; in all other games, characters sleep longer when they have taken more damage. Except in the original Super Smash Bros., the duration of sleep can be decreased by button mashing. Additionally, a character immediately wakes up if they are hit by an attack that causes flinching or the ground disappears.
Uniquely, Donkey Kong cannot fall asleep while carrying a heavy item. Additionally, in Brawl he cannot fall asleep while carrying an opponent, but he can in Melee.
In the original Super Smash Bros., Jigglypuff's Sing was the only way that characters could be put to sleep. The animation for sleeping characters was also the same as the animation for when stunned, except that the sleeping character flashes different colors, emits musical notes (as if they were hypnotized by the song), and uses a different voice clip, such as Mario snoring like in Super Mario 64 instead of constantly saying "Uuh!".
From Melee onward, all characters have a unique sleeping animation. For example, Donkey Kong rocks on his back and puts his thumb in his mouth, and Fox curls up on the ground like his real-world animal counterpart. In Ultimate, Steve takes out a Bed from Minecraft and lies upon it, then breaks it and places it back in his inventory upon waking up. Sleeping characters also flash magenta, and they also emit stylized "bubbles" from their faces. In Melee, Mr. Game & Watch emits stylized Z's instead of bubbles; from Brawl onward, both the bubbles and Z's are shown.
In Melee only, Mario, Luigi, Dr. Mario, Captain Falcon, Sheik, Yoshi, Bowser, Ganondorf, Young Link and Mr. Game & Watch emit their stun voice clip upon waking up without being interrupted by knockback. Starting with Smash 4, most newcomers and a number of veterans also have a similar (albeit unique) voice clip, often being a gasp or a quiet breathe; in Smash 4, this applied to most voiced newcomers (with the exception of Rosalina & Luma, Greninja, Bowser Jr., Lucina, Dark Pit and Duck Hunt) plus Mewtwo; Ultimate adds all voiced newcomers from that game (minus Inkling and Ridley; including Daisy and Chrom, whereas their base counterparts don't have one), as well as Link, Young Link, Zelda, Ganondorf, Wolf, and the Mii Fighters.