The infinite Tsukuyomi has the same foundation, however appears to be fixed as it functions by sorting all the information in the victims subconscious mind to result in an endless array of benevolent occurrences; a good dream that lasts forever which inevitably results in a change in emotions. If an individual had a dream that affected their emotions to a great extent, then this may affect their behavior when they 'wake up' (something I'm sure we have all experienced at some point) and this interprets that the dream affected your subconscious mind and at that extent also determines your behavior when you wake up in reality.
However, the root of the dream is the Casters Infinite Tsukuyomi which is designed to fabricate such fake occurrences in the mind. The happiness cannot be real if it was all a fabricated dream. It's been theorized that 'dreams' serve the purpose of organizing the information you received throughout the day in your subconscious mind; assuming this is true, everything experienced within the Infiinite Tsukuyomi must be, fake.