The Nightmare Cycle is a state of magical flux associated with the Ruins. Nightmare Lights (and Nightmare Fissures) open and close with the cycle, spawning hostile Shadow Creatures, regardless of the player's Sanity.
There are four phases of the Nightmare Cycle: the Calm Phase, Warning Phase, Nightmare Phase, and Dawn Phase. The entire cycle lasts 600 seconds (00:10:00).
Calm Phase[]

Appearance of Runic Turf during the Calm Phase.

–Wilson, inspecting a Thulecite Medallion during calm phase.

–Willow, inspecting a Thulecite Medallion during calm phase.

–Wolfgang, inspecting a Thulecite Medallion during calm phase.

–Wendy, inspecting a Thulecite Medallion during calm phase.

–WX-78, inspecting a Thulecite Medallion during calm phase.

–Wickerbottom, inspecting a Thulecite Medallion during calm phase.

–Woodie, inspecting a Thulecite Medallion during calm phase.

–Maxwell, inspecting a Thulecite Medallion during calm phase.

–Wagstaff, inspecting a Thulecite Medallion during calm phase.

–Wigfrid, inspecting a Thulecite Medallion during calm phase.

–Webber, inspecting a Thulecite Medallion during calm phase.

–Walani, inspecting a Thulecite Medallion during calm phase.

–Warly, inspecting a Thulecite Medallion during calm phase.

–Woodlegs, inspecting a Thulecite Medallion during calm phase.

–Wilba, inspecting a Thulecite Medallion during calm phase.

–Wormwood, inspecting a Thulecite Medallion during calm phase.

–Wheeler, inspecting a Thulecite Medallion during calm phase.

–Winona, inspecting a Thulecite Medallion during calm phase.

–Wortox, inspecting a Thulecite Medallion during calm phase.

–Wurt, inspecting a Thulecite Medallion during calm phase.

–Walter, inspecting a Thulecite Medallion during calm phase.

–Wanda, inspecting a Thulecite Medallion during calm phase.
- The Calm Phase will be active for 285–345 seconds (00:04:45 - 00:05:45)
- Nightmare Lights are closed (Shadow Creatures do not spawn)
- Runic Turf is blue
- No ambient sound can be heard in the background
Warning Phase[]

Appearance of Runic Turf during the Warning Phase.

–Wilson, inspecting a Thulecite Medallion during warning phase.

–Willow, inspecting a Thulecite Medallion during warning phase.

–Wolfgang, inspecting a Thulecite Medallion during warning phase.

–Wendy, inspecting a Thulecite Medallion during warning phase.

–WX-78, inspecting a Thulecite Medallion during warning phase.

–Wickerbottom, inspecting a Thulecite Medallion during warning phase.

–Woodie, inspecting a Thulecite Medallion during warning phase.

–Maxwell, inspecting a Thulecite Medallion during warning phase.

–Wagstaff, inspecting a Thulecite Medallion during warning phase.

–Wigfrid, inspecting a Thulecite Medallion during warning phase.

–Webber, inspecting a Thulecite Medallion during warning phase.

–Walani, inspecting a Thulecite Medallion during warning phase.

–Warly, inspecting a Thulecite Medallion during warning phase.

–Woodlegs, inspecting a Thulecite Medallion during warning phase.

–Wilba, inspecting a Thulecite Medallion during warning phase.

–Wormwood, inspecting a Thulecite Medallion during warning phase.

–Wheeler, inspecting a Thulecite Medallion during warning phase.

–Winona, inspecting a Thulecite Medallion during warning phase.

–Wortox, inspecting a Thulecite Medallion during warning phase.

–Wurt, inspecting a Thulecite Medallion during warning phase.

–Walter, inspecting a Thulecite Medallion during warning phase.

–Wanda, inspecting a Thulecite Medallion during warning phase.
- The Warning Phase will be active for 60–90 seconds (00:01:00 - 00:01:30)
- Nightmare Lights open up slightly (Shadow Creatures do not spawn)
- Runic Turf is gray
- A quiet ambient sound can be heard in the background
- Ancient Statues begin to glow
Nightmare Phase[]

Appearance of Runic Turf during the Nightmare Phase

–Wilson, inspecting a Thulecite Medallion during waxing nightmare phase.

–Willow, inspecting a Thulecite Medallion during waxing nightmare phase.

–Wolfgang, inspecting a Thulecite Medallion during waxing nightmare phase.

–Wendy, inspecting a Thulecite Medallion during waxing nightmare phase.

–WX-78, inspecting a Thulecite Medallion during waxing nightmare phase.

–Wickerbottom, inspecting a Thulecite Medallion during waxing nightmare phase.

–Woodie, inspecting a Thulecite Medallion during waxing nightmare phase.

–Maxwell, inspecting a Thulecite Medallion during waxing nightmare phase.

–Wagstaff, inspecting a Thulecite Medallion during waxing nightmare phase.

–Wigfrid, inspecting a Thulecite Medallion during waxing nightmare phase.

–Webber, inspecting a Thulecite Medallion during waxing nightmare phase.

–Walani, inspecting a Thulecite Medallion during waxing nightmare phase.

–Warly, inspecting a Thulecite Medallion during waxing nightmare phase.

–Woodlegs, inspecting a Thulecite Medallion during waxing nightmare phase.

–Wilba, inspecting a Thulecite Medallion during waxing nightmare phase.

–Wormwood, inspecting a Thulecite Medallion during waxing nightmare phase.

–Wheeler, inspecting a Thulecite Medallion during waxing nightmare phase.

–Winona, inspecting a Thulecite Medallion during waxing nightmare phase.

–Wortox, inspecting a Thulecite Medallion during waxing nightmare phase.

–Wurt, inspecting a Thulecite Medallion during waxing nightmare phase.

–Walter, inspecting a Thulecite Medallion during waxing nightmare phase.

–Wanda, inspecting a Thulecite Medallion during waxing nightmare phase.
- The Nightmare Phase will be active for 150–210 seconds (00:02:30 - 00:03:30).
- Nightmare Lights open up completely (Nightmare Creatures will spawn).
- Runic Turf cracks glow red.
- A loud ambient sound can be heard in the background.
- Earthquakes occur most frequently during this state.
- Ancient Statues are distorted, glowing brightly, with Nightmare Fuel seeping from their eyes and mouths. Mining them yields a chance of spawning a Shadow Creature from them.
- Splumonkeys transform into hostile Shadow Splumonkeys.

–Wilson, inspecting a Thulecite Medallion during steady nightmare phase.

–Willow, inspecting a Thulecite Medallion during steady nightmare phase.

–Wolfgang, inspecting a Thulecite Medallion during steady nightmare phase.

–Wendy, inspecting a Thulecite Medallion during steady nightmare phase.

–WX-78, inspecting a Thulecite Medallion during steady nightmare phase.

–Wickerbottom, inspecting a Thulecite Medallion during steady nightmare phase.

–Woodie, inspecting a Thulecite Medallion during steady nightmare phase.

–Maxwell, inspecting a Thulecite Medallion during steady nightmare phase.

–Wagstaff, inspecting a Thulecite Medallion during steady nightmare phase.

–Wigfrid, inspecting a Thulecite Medallion during steady nightmare phase.

–Webber, inspecting a Thulecite Medallion during steady nightmare phase.

–Walani, inspecting a Thulecite Medallion during steady nightmare phase.

–Warly, inspecting a Thulecite Medallion during steady nightmare phase.

–Woodlegs, inspecting a Thulecite Medallion during steady nightmare phase.

–Wilba, inspecting a Thulecite Medallion during steady nightmare phase.

–Wormwood, inspecting a Thulecite Medallion during steady nightmare phase.

–Wheeler, inspecting a Thulecite Medallion during steady nightmare phase.

–Winona, inspecting a Thulecite Medallion during steady nightmare phase.

–Wortox, inspecting a Thulecite Medallion during steady nightmare phase.

–Wurt, inspecting a Thulecite Medallion during steady nightmare phase.

–Walter, inspecting a Thulecite Medallion during steady nightmare phase.

–Wanda, inspecting a Thulecite Medallion during steady nightmare phase.

–Wilson, inspecting a Thulecite Medallion during waning nightmare phase.

–Willow, inspecting a Thulecite Medallion during waning nightmare phase.

–Wolfgang, inspecting a Thulecite Medallion during waning nightmare phase.

–Wendy, inspecting a Thulecite Medallion during waning nightmare phase.

–WX-78, inspecting a Thulecite Medallion during waning nightmare phase.

–Wickerbottom, inspecting a Thulecite Medallion during waning nightmare phase.

–Woodie, inspecting a Thulecite Medallion during waning nightmare phase.

–Maxwell, inspecting a Thulecite Medallion during waning nightmare phase.

–Wagstaff, inspecting a Thulecite Medallion during waning nightmare phase.

–Wigfrid, inspecting a Thulecite Medallion during waning nightmare phase.

–Webber, inspecting a Thulecite Medallion during waning nightmare phase.

–Walani, inspecting a Thulecite Medallion during waning nightmare phase.

–Warly, inspecting a Thulecite Medallion during waning nightmare phase.

–Woodlegs, inspecting a Thulecite Medallion during waning nightmare phase.

–Wilba, inspecting a Thulecite Medallion during waning nightmare phase.

–Wormwood, inspecting a Thulecite Medallion during waning nightmare phase.

–Wheeler, inspecting a Thulecite Medallion during waning nightmare phase.

–Winona, inspecting a Thulecite Medallion during waning nightmare phase.

–Wortox, inspecting a Thulecite Medallion during waning nightmare phase.

–Wurt, inspecting a Thulecite Medallion during waning nightmare phase.

–Walter, inspecting a Thulecite Medallion during waning nightmare phase.

–Wanda, inspecting a Thulecite Medallion during waning nightmare phase.
Dawn Phase[]

Appearance of Runic Turf during the Dawn Phase.

–Wilson, inspecting a Thulecite Medallion during dawn phase.

–Willow, inspecting a Thulecite Medallion during dawn phase.

–Wolfgang, inspecting a Thulecite Medallion during dawn phase.

–Wendy, inspecting a Thulecite Medallion during dawn phase.

–WX-78, inspecting a Thulecite Medallion during dawn phase.

–Wickerbottom, inspecting a Thulecite Medallion during dawn phase.

–Woodie, inspecting a Thulecite Medallion during dawn phase.

–Maxwell, inspecting a Thulecite Medallion during dawn phase.

–Wagstaff, inspecting a Thulecite Medallion during dawn phase.

–Wigfrid, inspecting a Thulecite Medallion during dawn phase.

–Webber, inspecting a Thulecite Medallion during dawn phase.

–Walani, inspecting a Thulecite Medallion during dawn phase.

–Warly, inspecting a Thulecite Medallion during dawn phase.

–Woodlegs, inspecting a Thulecite Medallion during dawn phase.

–Wilba, inspecting a Thulecite Medallion during dawn phase.

–Wormwood, inspecting a Thulecite Medallion during dawn phase.

–Wheeler, inspecting a Thulecite Medallion during dawn phase.

–Winona, inspecting a Thulecite Medallion during dawn phase.

–Wortox, inspecting a Thulecite Medallion during dawn phase.

–Wurt, inspecting a Thulecite Medallion during dawn phase.

–Walter, inspecting a Thulecite Medallion during dawn phase.

–Wanda, inspecting a Thulecite Medallion during dawn phase.
- The Dawn Phase will be active for 15–45 seconds (00:00:15 - 00:00:45)
- Nightmare Lights remain open (Nightmare Creatures will spawn)
- Runic Turf is gray
- A quiet ambient sound can be heard in the background
- Ancient Statues continue to glow
- Splumonkeys remain hostile Shadow Splumonkeys
Caves[]

A Fissure in a Cave floor as the Nightmare Cycle leaks through.
The Nightmare Cycle can also leak through to the Caves, in the form of Nightmare Fissures (similar to those found in the Ruins starting area). Nightmare Fissures are cracks in the floor that open and close, spawning Shadow Creatures the same way Nightmare Lights do. They are surrounded by an aura of white light and emit a bright red light. Note that while Fissures in the Caves will open and close independent of each other and independent of the Nightmare Cycle in the ruins, Fissures in the ruins will all be synchronized with the Nightmare Cycle.
Don't Starve Together[]
The duration of the cycles varies in DST.
Calm: 6 to 7.5 minutes
Warning: 1.5 to 3 minutes
Nightmare: 2.5 to 4 minutes
Dawn: 1 to 2.5 minutes
In Don't Starve Together, the Atrium Biome that was introduced in A New Reign is also affected by the Nightmare Cycle. Upon activating the Ancient Gateway by inserting the Ancient Key, the Cycle will be locked at its peak phase and will not change unless the Gateway is deactivated.
Tips[]

Using a Bush Hat to avoid Shadow Creatures.
- Players can avoid getting attacked by Shadow Creatures in the Nightmare Phase by remaining away from the Nightmare Lights and Nightmare Fissures. During the Warning Phase, they can move to a location (particularly the Wilds) where they are a safe distance away (slightly past the character's line of sight, and away from Splumonkeys) and remain there until the cycle ends. The Shadow Creatures that spawn will remain by the Lights and Fissures and do not wander, therefore will not seek the character out nor chase them. Standing on glowing Runic Turf is safe.
- A Bush Hat or Snurtle Shell Armour can be used just before the Nightmare Phase starts in order to avoid the Shadow Creatures that spawn.
- The Nightmare Lights will appear on the map, giving players an overall visual of safe versus dangerous areas.
- Hammering down the Splumonkey Pods and killing the Splumonkeys will permanently remove them. During the Nightmare Phase they become Shadow Splumonkeys, a hostile creature, and chase players until the end of the phase. As Splumonkeys are a major challenge during the Nightmare Phase, it is beneficial to remove their pods which will allow for larger areas of safety, especially when kiting Shadow Creatures.