I think you can incubate a bad dream, but true nightmares just happen. Like you can put more blankets on your bed to raise the temperture, and suspect people of being murders to create a creepy dream, but a really nightmarish dream I think is the result of supressed emotions during the day and in your life. Your unconcious is trying to get your attension that something is seriuosly wrong by using the emotion of fear.
Just my opinion though.
I always get nightmares if I take alot of B-vitamines before going to sleep. I take a pill that has 50 milligrams and 50 micrograms of all of the B-vitamines. It’s a goodish way to do WBTB 
because I’m usually scared for a while and I can’t fall asleep again for several minutes.
Certain movies will do it for me. In fact, I watched the movie Mimic for the first time a few years ago and recall being attacked by the bug-things in a dream.
I haven’t had a nightmare in a long time either touches wood
Inducing it is just a matter of finding something that terrifies you witless. Then your subconscious does the rest
Nightmares are easy.
Just conjure up a computer with Windows 98 installed and let the BSoD take over. 
Does anyone know what drugs (legal) may cause nightmares…Ive heard Vicodin or a generic version of the drug causes it.
hmm… I found the first to be one of the scariest… #3 with the lucid dream powers (?) was pretty good, I don’t remember if it was SCARY or not, but one of them centered around a school or hospital where Freddy is coming in to kill some kid, and you see him creeping up by the bed, but then he wakes up… that one freaked me out a little when I first saw that scene.
I still have an occasional dream about Freddy, once… I was at Disneyland, riding a crazy version of space mountain, and when I got out and was wandering the gift store I see him walk by… I’m a little surprised and I’m like “hey Freddy” … then I think “why the hell did you say that, now he’ll come after you” so I just tried to push him out of my mind…
then I think I stole stuff from the store.
… someone said think of something that terrifies you until you fall asleep… that got me thinking, what if you did that, what if you constantly forced yourself to think of things that you are just damn phobic of, over and over again? There would HAVE to be a point where your mind says ENOUGH and something interesting happens to you… like … passing out… having an NDE, or … completely curing yourself of fear?
If you want a wierd nightmare, play E rated games for three days. I once was going crazy on Crash Bandicoot and I had a nightmare about running from some invincible giant head thing that could go through anything in a Spyro world, it was terrifying cuz there was no excape.
this may sound odd, but sleeping naked caused me to have a nightmare.
i don’t normally sleep naked.
you dont have to stuff yourself til its painful to have a nightmare. just eat something substantial-not just some crackers or a cookie, i mean eat like a sandwhich or something…it also helps if you eat something spicy-put lots of mustard or jalepenos on it ect-and as soon as you’ve eaten-go to sleep. dont wait for your food to digest-just go to sleep. i’ve noticed since i was a kid that if i ate before bed, especially if i ate spicy or tangy food, i’d have a nightmare, and its still true today.
I almost always eat before bedtime and I have near zero nightmares … but perhaps i’m odd 
Indeed,seems like we-oddppl can sleep naked with full stomaches and still dream about plains full of pink flowers:)doh
Lol indeed Jack
Someone told me that, in the XIX century, gothic writers used to eat a lot of cheddar cheese before sleeping in order to induce nightmares.
Hehe…eat psychedelics in town with loads of people around you staring at you! hehe … (not sure which ones are legal though, it actually depends where you are located, Mushrooms are legal in some places for example.).
ANyway, last night I went to see Hide and seek … that was really scary for me,even going to the bathroom was already a nightmare hehe. My friend told me not to eat any cheese when I get home else I will have a night mare related to that movie.
SO I straight away went to the kitchen and ate LOADS of cheese 
(just to proove him wrong…) and went to bed.
I was waking up in HORROR every half an hour !!! 
So my advice is: Watch scary movie, and then eat cheese! 
I didn’t really get into the nightmare! I chickened the dream out…
I was trying to wild and after entering a lot of dreams and being kicked out because my censure-mechanism didn’t alow me i started thinking about bad things. My repressed rage, disturbing moments, fears, etc. The next hipnagogic images i kicked out where terroriffic! Like the aunted-house(from the fun-fair) pictures but really skary with ugly faces that grew bigger and bigger! I got lucid and kicked out of the dream. I had to calm down and think about nice things like sex to change the dream senarios.
Don’t know if you got the point…Try wilding into a nightmare and then if you want to forget lucidity!
Hope I helped… 