I haven't been sleeping well. Again. If asked, I tell people it's because I'm pre-occupied with work but, truthfully, it's because I've been having a lot of nightmares. Often, they're so realistic that I wake up feeling exhausted, battered, anxious, even afraid. Sometimes they're explicit and brutal, other times they're surreal and symbolic. Mostly, they're just plain bad and it takes me a while to get over them, to banish their memory. It's not easy. Deep in sleep, my mind and body still react as if each experience was real. Upon waking, it can be hard to distinguish dream from reality.A few months ago, I read in a Thai newspaper that police were investigating the death of a Thai worker in Taiwan. He had passed away mysteriously in his sleep. The Taiwanese police suspected it might be a case of Nightmare Death Syndrome. According to the article, Nightmare Death Syndrome is recognised as the leading cause of death in young men in Thailand, Laos, Cambodia, the Philippines, and Japan. The largest number of such deaths occur in north-east Thailand and Laos. In the Philippines, the syndrome is known as banungut – which is also the word for 'nightmare' – and in Japan, pokkuri disease. The Thais call it laitai.Many Thais believe that young men can be the victims of 'widow ghosts' that claim their lives to ease the widows' loneliness. The Hmong people (many of whom live in Loas and north-east Thailand) ascribe the deaths to a malign spirit, dab tsong, who is said to take the form of a jealous woman. Apparently, Hmong men might sleep dressed as a women to avoid the female spirit's attentions. The syndrome is also recognised in the USA, where it's referred to as Sudden Unexplained Death Syndrome, as being specific to immigrants from Southeast Asia. There are various western studies attributing the deaths to tropical seasons and location but all fail to explain why so many immigrants died of the complication after they had left those situations.I'm not afraid of dying in my sleep. My nightmares have simply sharpened my empathy with Southeast Asian superstitions and beliefs. In the developed world, having acutely realistic dreams is, according to my psychiatrist, one of the the symptoms of a mental illness. However, other cultures are not so quick to dismiss the possibility – and taxing effect – of heightened sensitivity, visions, and metaphysics. The link between art and madness is a popular Western cliché but only in Asia is the step from art (and madness) to an alternative reality a common element of the everyday.