Residents of a small village in northern Kazakhstan are being evacuated after being plagued with a long running 'sleeping sickness'.
Over a tenth of residents in the Kalachi village, dubbed as 'Sleepy Hollow', are affected by the illness that triggers sudden sleep spells in the middle of the day.
Residents have sometimes been reported to fall asleep for weeks.
The first case was reported in March 2013 with symptoms, including hallucinations, memory loss, dizziness and nausea.
"When the patient wakes up, he will remember nothing," Dr. Kabdrashit Almagambetov told The Siberian Times.
"The story is one and the same each time – weakness, slow reactions, then fast asleep. The sleep is so deep that some locals fear an old man they assumed was dead could have been buried alive."
Several doctors and scientists from virologists and radiologists to toxicologists have visited the village in an attempt to figure out the mystery illness but failed.
Samples have also been taken of the soil, air and water in the village, as well as the affected peoples' blood, hair and nails, without any luck, reported MSN News.
Meanwhile, the director of Kazakhstan's National Nuclear Center's Radiation Safety and Ecology Institute, Sergei Lukashenko, fears the "peculiar" geographic location of the village where chimney smoke goes down instead of going up could be the cause.
"Carbon monoxide is definitely a factor. But I can't tell you whether this is the main and vital factor," said Lukashenko.
However, others disagree, including Professor Andrew Stolbach, the head of toxicology at Johns Hopkins Hospital.
"Carbon monoxide poisoning doesn't just make you fall down and go to sleep," said Stolbach.