More than 7,000 experiments into the soil, air, water and patient's blood, hair and nails have been carried out by scientists in these remote villages.
But so far, all results have come back inconclusive - although scientists fear leaking uranium could be to blame.
Aside from the sleeping, other symptoms include weakness, dizziness and memory loss and children have reported seeing terrifying hallucinations.
The sleep epidemic has affected around 60 people so far, and it is thought to have started in March 2013.
Since then there have been repeat "waves" of the epidemic, in May 2013, New Year 2014 and most recently now, in May 2014.