Old Hag' Syndrome is a terrifying sleep disorder that many people suffer from. Also known as 'sleep paralysis', sufferers often wake up in the middle of the night, unable to move or scream, but able to see, hear, feel and smell. It is often accompanied by strange smells, frightening sounds, apparitions of shadows or people, and a weight on the chest, making breathing difficult if not impossible. It is caused by the hormones, which keep us paralysed while we sleep and thus preventing us from acting out our dreams, not ceasing function immediately when you wake up. It usually only lasts up to a minute.