Ideyas (pronounced ih-dee-yah) are colored, crystalline orbs representing dream energy. The Nightmarens steal this energy from Visitors to further their goal of destroying Nightopia. Each time an Ideya is stolen, Nightopia disappears bit by bit. Ideya represents the Visitor's consciousness in the Night Dimension. Every dreamer possesses five of them, as stated by Owl in NiGHTS: Journey of Dreams, although it is often stolen by Nightmarens on the way to the Night Dimension. The name is a play on the word idea.
Nightmarens also cannot steal the visitors' red ideya.
The Five Ideya
Red Ideya of Courage
Red Ideya represents Courage. It is the rarest type of dream energy and the only type that the Nightmarens cannot steal. However, in NiGHTS: Journey of Dreams, Wizeman is able to steal the Red Ideya from Helen in the level Bellbridge; Will was able to restore her courage and the Red Ideya. Only a Red Ideya is capable of releasing NiGHTS from imprisonment. Embedded in NiGHTS' chest is a Red Ideya shaped like a diamond to represent that the rebellious jester had from a previous visitor who possesses an ideya of courage that was broken in the mini-series comic.
White Ideya of Purity
"This white light... its the White Ideya. This was the purity that was missing from my heart." Will in Journey of Dreams.
"The White Ideya... The reflection of a pure heart. Is this my... heart?" Helen in Journey of Dreams.
White Ideya represents Purity within the visitor's heart.
Blue Ideya of Intelligence
"The Blue Ideya, symbol of intelligence. I can feel it filling my mind." Will in Journey of Dreams.
"The Blue Ideya, which governs intelligence... Another lost piece... of my heart." Helen in Journey of Dreams.
Blue Ideya represents the dreamer's Intelligence.
Green Ideya of Growth
"The Green Ideya, which stimulates growth in the heart. My biggest dream, my future." Will in Journey of Dreams.
"The Green Ideya, a symbol of growth. My future, nurtured by my memories." Helen in Journey of Dreams.
Green Ideya represents Growth and Wisdom.
Yellow Ideya of Hope
Yellow Ideya represents Hope.
Outside of the NiGHTS series, the ideyas appeared in Sonic Adventure in the NiGHTS Pinball table where the player can collect all of them and if they do, they'll be rewarded with 300 rings,  they also make a cameo in Sonic Pinball Party, in the NiGHTS' tables and in Sonic Runner, the red ideya appeared as a buddy for a limited time, in Billy Hatcher and the giant egg, there's a light orb which looks very similar to the white ideya and in Sonic Lost World, in the Nightmare Zone, there's a red orb in Gillwing's tail which looks very similar to the red ideya.
- In the platform game Billy Hatcher and the Giant Egg for the Gamecube, which was also developed by Sonic Team, the final boss from the game, Dark Raven, will shoot a dark orb at Billy during the second part of his boss battle, when Billy touches the orb to turn it into a light orb, the orb will turn into a white orb which looks very similar to the White Ideya.