Slumber

When all players that are not spectators are sleeping, Slumber runs extra full ticks for the server. Time-dependent progress in the world keeps moving during that span, and this applies to every loaded dimension, including the Overworld, the Nether and the End, along with modded ones. A player who is not asleep, or who is in spectator mode, does not trigger it.

Slumber works on dedicated servers and in integrated singleplayer, so a single-player world uses the same sleep flow. While the feature is active, the vanilla instant night skip is temporarily disabled and is restored afterward. The speed is set per world with the slumberTickMultiplier gamerule, which defaults to 30 and can be read or changed like any other gamerule.

Slumber is published for Fabric, Forge and NeoForge across six release versions, 1.21.1 – 1.21.10, and is licensed under the MIT License, so the code is open source. Players join without it, since only the server has to run the mod. Its source code and issue tracker are public, and the author asks that reports include logs, reproduction steps and performance or compatibility details.