the night hag
According to the old believes, The Night hag is a female demon who can come in many forms during the night to give person nightmares and scare him. Sometimes it is a dark mass or a shadow seen on person’s chest or neck during the night. The person attacked by a night hag is restless, grunts, tosses himself in sleep, has hard time breathing, grabs his chest and when he wakes up often says that something was strangling him in sleep. The defense against night hags was closing keyholes through which they came into the room.