During the live stream viewers saw Hori snore and later sleep for about 27 minutes while receiving a head massage. By the second day his eyes looked blood‑shot, and by the third he began wearing sunglasses, clear signs of sleep deprivation.

Dr. Mikiya Takasu, director of the Nagoya branch of Takasu Clinic, called the experiment a failure, noting that Hori was obviously exhausted and lacking real sleep.

Professor Masashi Yanagisawa of the University of Tsukuba explained that genuine short sleepers are determined by genetics, occur in only a few thousand people, and cannot be trained. He added that more than 99% of self‑described short sleepers are not authentic.

Sleep specialist Masahiko Atsumi said a single all‑night sleepless period makes substances suspected of causing dementia more likely to build up in the brain. He also warned that chronic short sleep is linked to depression, damage to blood vessels in the heart and brain, and higher mortality.

A 2018 study by the U.S. National Institutes of Health found that missing just one night of sleep raised beta‑amyloid levels by about 5% in the thalamus and hippocampus, brain areas involved in Alzheimer’s disease.

The U.S. National Sleep Foundation still recommends that adults aged 18 to 64 get seven to nine hours of sleep each night.