Day-Night Cycle

"It's getting late. I need to make a fire."

- Wilson A full Day lasts for 8 real-time minutes (split into 16, 30-second segments) and is divided into 3 phases. The Day phase is the brightest and is represented by the yellow segments of the clock in the top-right corner of the screen. Dusk is shown by red segments and is the part of the day when the sun is setting and the world becomes darker, although a light source is not yet required. When Night falls, the world quickly becomes completely dark and a light source is necessary. Night is represented by blue segments on the clock.

Day
The lightest portion of the Day is generally the safest and also the time when most Animals are active. Spiders and Spider Warriors sleep during the Day, and Pigs roam outside their houses. Merms are less common during the Day phase, and this is the only time Red Mushrooms sprout up to be picked. Crops in Farms are only grown in daylight.

Dusk
At Dusk, Bees, Butterflies, Frogs, Gobblers, Pigs, Rabbits, and Tallbirds all return to their homes until morning. Spiders and Mosquitoes become active at this time while Beefalo move closer together as a herd. Merms are much more active at Dusk than any other phase. Bunnymen will also come out of their houses during this phase and stay out until daybreak. Pigs who are trapped outside at Dusk will panic and run around searching for light. The temperature begins to drop as well, and Green Mushrooms sprout to be picked. Dusk drains a character's Sanity by 5/minute.

Night
When Night falls, the world quickly turns black. Most neutral and passive mobs still outside go to sleep on the spot. Redbirds, Snowbirds, and Crows who do not take flight before night comes settle down to sleep. Most aggressive mobs continue to be active at night. A light source is required during this phase not only to see, but also because the Night Monster (AKA the Grue or Charlie) will attack in complete darkness. Also, in total darkness, the character cannot interact with anything, including putting Campfires and Fire Pits down, and Sanity drains at rate of 50/minute. While close to an active light source, sanity drains at 5/minute. Night is the coldest phase and the time when Blue Mushrooms, the rarest of the three mushrooms and a potent healing item, may be picked.

Mob activity
Surface mobs not listed here have the same behavior throughout the day, despite the phase.

Seasons

 * Note: This section relates to Sandbox/Survival mode only.

The amount of daylight varies throughout the game. In mid-Summer (starting around Day 3) the Day phase is more than half of the total clock, while Night lasts only 2 segments. In Winter, Night is about 1/3 of the clock and Dusk nearly half. One complete cycle of the seasons lasts 36 days; 20 Summer and 16 Winter. Below is a chart showing the amount of each phase throughout the seasons:



Caves
Caves have a unique Day-Night Cycle. Time doesn't pass the same as it does on the surface, but there's still a Day-Night cycle. The only way to tell which phase it is, is from the natural shafts of light. The lighted area becomes more narrow with each phase until darkness engulf the area at night. The player still loses sanity as if it were night despite the phase. Mob activity during the phases is the same as on the surface. Naturally, Seasons do not impact caves with day length (as there is no day) or temperature. Players who are freezing from the cold warm up as soon as they go underground.

Trees, Saplings, Grass, and Berry Bushes grow as they do on the surface, but the player is blind to the passage of time while underground. Crops will only grow if they are near a light source, though they can still grow with the help of fertilizer.

Ruins
Ruins have their own cycle called the Nightmare Cycle. They are still considered as perma-night, and mob activity abides to the night phase, but the ruins have their own phases which are signaled by the Ancient Statues and Nightmare Lights. For more information please read : Nightmare Cycle.

Reign of Giants icon.pngReign of Giants
Nights are slightly longer in Reign of Giants and the number of segments per phase changes drastically from vanilla game depending on season.

Bug

 * When hovering the mouse over the Clock during Dusk, it will not show you the number of the world you're in.