Hypnagogic hallucinations are vivid sensory experiences that occur during the transition from wakefulness to sleep. They can involve seeing, hearing, or feeling things that are not actually present. These hallucinations are often brief and can be accompanied by a sense of fear or confusion. These experiences are common and can happen to anyone, especially when sleep-deprived or under stress. They are not considered a mental health disorder but can be associated with conditions like narcolepsy. Understanding hypnagogic hallucinations can help individuals recognize them as a normal part of the sleep process.