Have you ever woken up in the middle of the night and been scared shitless thinking there's someone in your room? Usually, it just turns out to be a pile of old clothes that's assumed the shape of a scary nun. Usually. 

Sometimes, it's something far more sinister.

In Bengali culture, the Boba is a menacing entity that attacks people who are sleeping on their backs.

That's right, even chilling on your back isn't safe anymore. Assume the foetal position or die.

The Boba strangles its victims to death, and is believed to be a more supernatural explanation for sleep paralysis.

'Boba' actually means dumb/unable to speak, and this ghost is attributed to how it feels when you go through sleep paralysis, wherein the brain is functioning but the body is asleep. 

Source: Nerdist

That's the kind of pain the Boba feeds off - it takes a sick kind of pleasure in your helpless terror, in watching the life slip out of your eyes as you breathe your last, unable to defend yourself.

A person experiencing sleep paralysis is completely unable to move or speak, and hallucinates things like an old, scary witch or monster. It's torture.

Source: Express

The only way to avoid this cruel beast seems to be by lying on your side or stomach. And if you can't... well then I wish you sweet dreams.