Simulating the world while you sleep
Somnia Awoken is a Minecraft mod that simulates the world while you sleep. It is a port/rewrite of the mod Somnia, which was initially released in 2011.
Imagine skipping the night and wasting 10 hours of Minecraft time. Your furnaces won't smelt anything, and your crops won't grow. With Somnia, you make use of every tick. Put some ores into the furnace, sleep for a bit, then wake up to see them smolten.
Fatigue is a game mechanic used to control the player's sleep, ranging from 0 to 100. You can enter sleep at any time, but only if you have enough fatigue. It is displayed on the screen, in the position of your choice (bottom right by default). While the player's fatigue is updated every tick, the display is only updated every 5 seconds. If it drops below the required amount during sleep, you won't wake up.
It's recommended to watch your fatigue regularly, as getting too tired will result in some debuffs. These debuff will be applied only once for a certain period of time when you enter a new side effect stage. The last side effect is permanent.
The default side effects are:
Instead of skipping the night, the world is sped up while you sleep. This includes mob spawns, so it's recommended to find a shelter for the night. Alternatively, you can disable mob spawning while you're alseep in the config.

Somnia Awoken provides a way to select your wake time by right clicking a bed using a certain item (Default: clock). The Wake Time Selection GUI also lets you sleep without resetting your respawn point.

Somnia provides an enhanced sleeping GUI for tracking the sleep progress, simulation tick multiplier and ETA remaining sleep time.

Somnia adds an option to sleep normally, disabling simulation and skipping the night. To achieve this, sneak while entering a bed. This re-enables the default time check, so that you can only sleep at night. However, Somnia checks, such as the minimum fatigue to sleep, ignore monsters and armor, still apply. In multiplayer, Somnia will deactivate if most players choose to sleep normally.
The original author of Somnia is MALfunction84, who released it in 2011. Original thread here.
In around 2014, kingrunes ported the mod to newer minecraft versions 1.5, 1.6 and 1.7. Their thread is available via the Wayback machine.
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