11 Surprising Things That Affect Your Dreams

You hate how your mother-in-law meddles in your marriage, so it's no shocker when you tell her off in your dream—dreams are, after all, your brain's way of working through unresolved conflicts. But what can explain that recent string of random nightmares or incredibly vivid visions? "We know a bit about things that affect dream recall and make for more nightmares," says Deirdre Barrett, PhD, assistant clinical professor of psychiatry at Harvard Medical School in Boston, MA, and author of The Committee of Sleep. So here, 11 surprising things that can influence what pops up in your dreams or how likely you are to remember them.

1) Smells

Do sweet smells lead to sweet dreams? One small study found that sniffing flowers at a particular point in the sleep cycle led to more positive dreams, while a sulphur odor was linked to negative ones. Though researchers say you can't replicate those results in your bedroom (by the time you're dreaming, that lilac blossom scent you spritzed pre-bedtime can't stimulate you), there's a possibility that a sudden aroma—bacon wafting up from the kitchen, for example—could infiltrate your dream. "Dreams are sleep protective," says J. Catesby Ware, PhD, Chief of the Division of Sleep Medicine at Eastern Virginia Medical School, in Norfolk, VA. "So instead of waking up, you incorporate those stimuli into your dream."

2) Sounds

You wake up after dreaming you're stuck in a burning building—and realize that the fire alarm you heard was actually your alarm clock. What's with that? There's a narrow window for sounds to get through to your brain during sleep, says Dr. Barrett: "They need to be low enough that they don't wake you but highenough that you perceive them." So let a recording of ocean waves play softly throughout the night. You might recall a dream about a beach vacation or wake up feeling relaxed.

3) Spicy Food

t's simple: Anything that could cause indigestion—cheese, spicy foods, a big meal—makes you stir more, meaning you have a better shot of remembering that nightmare. "The rule of thumb is that you need to wake up within five minutes of having a dream to recall it," says Dr. Ware. For rest that's more peaceful all around, eat dinner at least two hours before bedtime, and choose nighttime snacks wisely (read: no Haagen-Dazs if you're lactose intolerant). Since caffeine can have the same disruptive effect, it's best to cut off your coffee intake post-2 p.m. too.

4) Sleeping on Your Stomach

Are you prone to racy dreams? Well, sleeping in the prone position (that is, on your stomach) might have something to do with it. A new studypublished in the Journal Dreaming found that lying on your belly in bed was linked to blush-worthy dream themes, like having sex with a celebrity or being tied up. Researchers hypothesize that it might have to do with your breathing patterns in this position. To stop the sexy thoughts—or keep 'em coming—adjust your sleep posture accordingly.

5) Vitamin B6

While there's no research on whether or not taking B6 leads to more lucid dreams, the Internet is awash with anecdotal reports that it does—which, according to Dr. Barrett, makes good biological sense. "B6 is the co-factor our body uses to turn some of the amino acids we eat into the neurotransmitters that affect our dreaming," she says. To stop the vivid dreams, stop the supplements. But if you're looking to encourage dreaming, stay within therecommended amount of B6 daily—too much could cause nerve damage or numbness over time.

6) Antidepressants

Yes, those pills that are supposed to calm you down—especially the SSRI (selective serotonin reuptake inhibitor) class of antidepressants, like Prozac, Paxil and Zoloft—might be upping your nightmares. "They've been shown to make REM bursts more intense in the people who take them," says Dr. Barrett, referring to rapid-eye movement sleep, the stage during which we dream. "And most of those people seem to have more nightmares as a side effect." If you're feeling tormented, talk to your doctor about switching to a similar drug. While all SSRIs can cause nightmares, Dr. Barrett says each variation tends to affect each person's brain differently.

7) Quitting Smoking

Vivid dreams have been shown to be a symptom of kicking the habit, and in one study, 63% of smokers still dreamed about smoking a year later. Granted, you may just be working through your main issue at the moment (the fact that youreally want a cigarette), but nicotine withdrawal also enhances brain activity in a way that can make you dream more, says Patrick McNamara, PhD, Director of the Evolutionary Neurobehavior Laboratory at the Boston University School of Medicine in Boston, MA. His advice: Stick it out. Those neurons will eventually calm down again—and your lungs will be much healthier.

8) Black and White Television

File under quirky but possibly true: If you grew up before color TV sets were commonplace, you might be more likely to recall your dreams in grayscale rather than color, according to one study by a British researcher. The sweet spot for being exposed to black-and-white media might be between about three and 10 years old (when most people start remembering their dreams), so there's not much you can do to change your dream palette now. Still, it's interesting to think about if you grew up on a steady diet of classic movies or I Love Lucy…

9) Going to Bed Hungry

You're struggling to keep yourself on that diet—and you might be having the dreams to prove it. Low blood sugar can rouse you from sleep, meaning you may remember more dreams and those dreams may star a juicy burger or a piping-hot piece of pizza. In fact, Dr. Ware's anorexic patients almost always dreamed about food in one sleep study. Luckily, a small nighttime snack of a banana and a glass of skim milk isn't just filling, healthy and waistline-friendly—it also contains tryptophan (the amino acid in turkey that makes people drowsy after Thanksgiving dinner), which can help you sleep more soundly.

10) Scary Movies

You've been hearing it since you were a kid: Spooky movies cause spooky nightmares. But is there any truth to that mom-knows-best scare tactic? Dr. Barrett says the last thing you do before bed matters, period. "The music you're listening to, the book you're reading, the TV show you're watching, the conversation you're having with your spouse—all those things are likely to be influencing," she says. So if you suffer from nightmares and happen to catch a horror flick, take a few minutes to reprogram your brain with happy thoughts—like vacation memories or favorite moments with your kids—before settling down to sleep.