When she was ten years old, she began to experience vivid hallucinations which she has described as «flashes of light, auras, or dense fields of dots». (en.wikipedia.org)
In the early phases of deep sleep, and during short daytime naps, which consist of pure non-REM sleep, people report vivid hallucinations that are shorter, more static and more thoughtlike than the dreams that occur during REM sleep. (scientificamerican.com)
His friends all agree to help after they start experiencing vivid hallucinations, where a terrifying supernatural clown shows them their worst fears realised. (lwlies.com)