The longest documented self-imposed hypnotic sleep is eight straight days, achieved by UK hypnotist Peter Powers in 1959.
This record highlights the fascinating, albeit potentially dangerous, exploration of the human mind's capacity for altered states of consciousness. While hypnotic sleep isn't the same as natural sleep, Powers' achievement underscores the limits – or perhaps lack thereof – of human endurance in specific, induced states. It's important to note that such extreme experiments are not recommended and carry significant health risks.
While there might be other records concerning different aspects of sleep (e.g., longest continuous sleep without waking, longest time spent in REM sleep), the provided reference focuses specifically on a hypnotic sleep record. Further research would be needed to identify records in other sleep categories.
