How to Induce Nightmares
If you want to induce nightmares, there are a few simple tricks you can try before bed to heighten your dreams. Try eating spicy, salty, or fatty foods before going to sleep, since these are known to increase dream intensity. You might also try lying on your stomach as you fall asleep, which might make you dream about being tied up or smothered. Another way to induce nightmares is to watch a horror movie before bed or play a scary video game. This will increase your anxiety before bed, which can lead to nightmares. If none of these methods work, consider taking melatonin before bed, which can make your dreams more vivid.
Sleep face down. A study from Hong Kong Shue Yan University shows that people who sleep face down are more likely to have dreams about being tied up, smothered, and other nightmarish themes. Note that this may also increase the likelihood of erotic or sexual dreams, so you may not receive the desired effect. If you cannot get to sleep on your stomach, the next most "nightmarish" sleeping position may be lying on your back, followed by lying on your left side. Try eating certain foods before bed. While eating spicy, salty, or fatty foods are commonly believed to cause nightmares, scientists are divided over the exact effect of these substances. Some argue that the disruption of your sleep cycle may even slow down the onset of dreaming, potentially resulting in fewer dreams or nightmares. Others think they may increase dream intensity, at least in some people, and suggest that each person pay attention to his own body's response. Scare yourself slightly before going to bed. Try watching a horror movie, playing a scary video game, or reading ghost stories before bed. If you have a specific fear or anxiety, look at images of it or simply lie in bed imagining a "nightmare scenario." Aim to make yourself only slightly scared or anxious. If you are terrified out of your wits, you are unlikely to fall asleep in the first place. Consider taking vitamin B6. While the effect of vitamin B6 on dreams is not thoroughly studied, many people swear by its ability to increase the vividness of dreams. One study suggests that it may be effective, either due to an effect on the dreaming process itself, or an enhancement of your ability to remember dreams. Including vitamin B6 from both food and supplements, daily intake should not exceed 60 mg for children 9–13 years old; 80 mg for teenagers 14–18 years old; or 100 mg for adults 19 years or older. Try taking melatonin. Some people report having more vivid or bizarre dreams when taking melatonin, which may give you a new dream experience even if they are not outright nightmares. At least one study supports this idea, suggesting that dreams involving transformations are especially likely to occur under melatonin. Melatonin is typically taken in doses of 1–20mg, and rarely causes health problems. However, due to interactions with other medications, possible negative effects during pregnancy, and the chance of an allergic reaction, you may wish to consult a doctor before taking melatonin. Take certain substances in moderation. Caffeine, alcohol, and nicotine can all disrupt your sleep cycle. This can potentially cause nightmares if taken in small quantities. However, ingesting any of these substances in too large a quantity can disrupt your sleep too much. Reduce your intake of these substances if you have difficulty falling asleep in the first place, if you wake up repeatedly in the night, or if you feel tired after waking up. These are all signs that you may be getting less restful sleep, which may reduce the amount you dream. If you rarely or never consume these substances, the effect is likely to be more potent than you expect. It is not recommended that you begin taking these drugs solely to induce nightmares. Think of a topic to dream about. As you fall asleep, try to think of an image or concept that causes fear or anxiety. If you attempt this every night, you have a good chance of dreaming about the subject of your thoughts. You may be able to make your dreams or nightmares beneficial if you have a problem to solve that is causing you anxiety; your brain may continue to "work on" the problem while you sleep, possibly providing insight during a dream. Sleep for eight hours or more each night. While inducing a nightmare on a given night may be helped by moderate sleep disruption, repeating that day after day may greatly reduce the number of dreams you have. Stay well-rested, and you will spend more time in the deeper, restful REM period of sleep, in which most lengthy dreams occur. REM is short for Rapid Eye Movement, which describes the behavior of people sleeping during this period of sleep. Lie in bed after waking up. Instead of getting up immediately, lie awake and try to remember or "replay" your dreams. If nothing comes to mind, try to examine your own emotions. If you wake up anxious or exhilarated, focusing on those feelings may help you remember a nightmare. Write down your dreams to increase the odds of remembering them. Every human dreams each time they fall asleep for an extended period of time, but many of these dreams go unremembered. Try to write your dreams in a notebook by your bed as soon as you wake up, before you forget them, to help them stick in your memory. Write down any dreams you remember, not just your nightmares, as the habit may help you remember later dreams. Try to cause lucid dreaming. In a lucid dream, the dreamer is aware that she is dreaming. This often results in a more vivid or memorable dream, and sometimes, but not always, allows the dreamer to shape the course of events to some extent. While there are many ways to encourage lucid dreaming , you can start with two simple steps: Focus on the concept of dreaming as you fall asleep, or about a particular topic to dream about. Choose the same topic each night for at least two weeks. Look for "reality checks" during the dream and your waking hours. Many people find that clocks or text in dreams can't be read clearly, or will look different each time. Try checking the time or reading a sign throughout the day as a "dream check," and you may notice yourself doing the same thing to identify that you are dreaming. 
Sleep face down. Try eating certain foods before bed. Scare yourself slightly before going to bed. Consider taking vitamin B6. Try taking melatonin. Take certain substances in moderation. Think of a topic to dream about. Sleep for eight hours or more each night. Lie in bed after waking up. Write down your dreams to increase the odds of remembering them. Try to cause lucid dreaming. 