After a restless night of sleep, filled with nightmares where velociraptors and chainsaw-wielding maniacs chase you down, you wake up and wonder what caused such vivid, frightful dreams. Could it have been that spicy Thai food you had before bed?

Actually, there is some evidence that eating a spicy meal shortly before going to sleep can lead to some wacko dreams. In fact, eating anything too close to bedtime can trigger more dreams, because the late night snacks increase the body’s metabolism and temperature, explains Dr. Charles Bae, MD, a sleep medicine doctor at Sleep Disorders Center at the Cleveland Clinic. Heightened metabolism and temperature can lead to more brain activity, prompting more action during rapid eye movement sleep, or REM.

About every 90 minutes people experience rapid eye movement sleep as they cycle through the stages of sleep. In REM, when people dream the most, the body’s muscle tone slackens. During REM the brain becomes active, like it does when awake, and the eyes flutter behind the lids. Nightmares only happen during REM and while nightmares are simply dreams with negative emotions, they stand apart because they rouse the sleeper. It’s one of the reasons why it’s easier to recall nightmares than run-of-the-mill dreams. While little is understood about nightmares, experts know that frequent nightmare sufferers often show dysfunction in the frontal lobe and it fails to control the amygdala, which regulates memory and emotions. Disturbances in these regions might impact people without problematic nightmares, contributing to vivid dreams.

So can that extra spicy Pad Thai lead to velociraptors tearing through your dreams?

Lisa Medalie, a clinical associate of psychiatry at University of Chicago Hospitals writes via email: “If our bodies are working hard to digest heavy or spicy foods, it interferes with sleep continuity. We typically advise patients to avoid heavy or spicy foods within [two to three] hours of their bedtime.”

It’s not a subject that has been studied often, but one Canadian report suggested that 8.5 percent of the 389 study subjects blamed bad dreams on food.

“It is … possible that spicy foods—or other foods such as dairy or greasy fast foods—at least occasionally induce nightmares or other bizarre dreams. It might be that some people are sensitive to the chemical composition of certain foods,” writes Tore Nielsen, professor at the Université de Montreal and director of the dream and nightmare laboratory at Sacré-Coeur Hospital, via email.

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Do you ever pick up something off the floor and eat it, citing the all-powerful five-second rule?

Well, that may be grosser than you think, depending on what kind of food it is. Between ham, a PBJ and pasta, which do you think soaks up the most bacteria in five seconds?

If you guessed the pasta, you're right. Foods with higher salt content are less likely to pick up bacteria, Kathie Lee shared, after one of each was tossed onto the studio floor. 

Then, she brought up a good point.

"Who's gonna eat pasta off the floor?" she asked.

Hoda said she wouldn't, but she might, if it was an Oreo.

Julieanne Smolinski is a TODAY.com contributor. She'd chase an Oreo into a live volcano.

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Mom's lasagna. Homemade chocolate chip cookies straight from the oven. Steak sizzling on the grill. Roasted turkey and stuffing. Flame-broiled hamburgers. Good-quality dark chocolate.

Is your mouth watering at the very thought of some of these foods? Sorry to break it to you, but a recent study found that humans are not able to salivate at the thought of food.

"We are not like dogs -- in particular, we're not like Pavlov's dogs -- and don't have conditioned salivary reflexes," says lead author Guy Carpenter.

In the small study, published in the Journal of Texture Studies, British researchers tried to determine if a mouthwatering sensation exists in humans at the suggestion of food. They rounded up 5 healthy people and first showed them pictures of different foods -- from pizza and Thai curry to grilled chicken and baked pasta.

Using cotton pads inside the cheeks and suction devices under the tongue, scientists collected saliva samples from participants as they viewed this visual feast.

Looking at photographs, which simulates thinking about food in real life, didn't increase the amount of saliva flowing from any of the major salivary glands, before or after eating a meal. In other words, a "mouthwatering sensation" wasn't seen in the participants whether they were hungry or not. 

Although food advertisers may want consumers to believe that pictures of food can have a mouthwatering influence, this study found it wasn't the case.

In another experiment, researchers observed how much moisture the mouth produced when volunteers could see and smell a bowl of hot noodles. And a third test, gathered saliva samples before, during, and after participants ate their lunch.

Smelling food's aromas increased saliva secretions more so than holding food or looking at pictures of it. But the largest quantities of spit flowed when participants actually tasted and chewed food.

"This study reinforces the idea that merely thinking of food doesn't cause a faster rate of saliva into the mouth," says Carpenter, a senior lecturer in oral and mucosal biology at King's College London Dental Institute.

Mouthwatering, he says, is not a true salivary reflex, meaning a stimuli that can increase saliva secretion for prolonged periods. Instead Carpenter proposes the mouthwatering sensation "is due to small squirts of saliva entering the mouth when facial muscles squeeze on dilated salivary ducts."

Carpenter says "to increase the anticipation and mouthwatering aspect" of a meal, "increase the smells." 

Readers, tell us what are the food smells that always make your mouth water?

Related:

Can eating too much make your stomach burst?

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You know how sometimes everyone is terrible and everything is the worst and nothing ever, ever, goes your way?

Chill out. You’re probably just hungry. Or, rather, hangry.

“Hanger” -- that’s with the hard /g/ sound -- or "food swings" are silly terms used to describe the treacherous intersection where hunger and anger collide. Ever stagger through a terrible morning, only to find yourself in much better spirits after lunch? Then you, my friend, have been hangry.

The cause of your “mad”-ness? Low blood sugar.

Marjorie Nolan is a spokeswoman for the American Dietetic Association. She explains that “hanger” isn’t just a ploy by crabby people to excuse their moods (and snag some snacks); it has a scientific explanation.

 “When [blood sugar] is low,” says Nolan, “the hypothalamus is triggered and levels of several hormones such as growth hormone, leptin and ghrelin are affected.  This imbalance then causes a shift in neurotransmitters and suppresses serotonin receptors.”

Serotonin is a hormone that helps regulate mood and appetite. Cut off your body’s ability to process it, and prepare for some mood swings. Anger and extreme frustration, Nolan says, are common responses.

This is not to say everyone who skips lunch will turn into The Hulk before dinner. Blood sugar has to drop pretty low (from a normal range of 70 to 100 milligrams per deciliter to a level below 55 mg/dL) before hanger-causing moderate hypoglycemia sets in. That takes several hours of not eating.

And, says Nolan, there are other factors that may make some people more susceptible to “hanger” than others.

“For individuals more prone to having low [blood sugar], symptoms tend to be more severe,” she explains. “‘Anger’ as a result of hunger is in part, personality based.  If you are someone who is more prone to feeling frustrated or ‘moody’ to other life situations you are more likely to have this reaction when hungry.” 

Outside stressors --like work or family issues-- can worsen the problem.

 “If you are already feeling on edge,” she adds, “chances are extreme hunger is going to personify this.”

In order to keep your blood sugar stable and ward off hanger, Nolan suggests eating a combination of protein and complex carbs every 3 hours. (Cheese and wheat crackers or hummus on pita will get the job done.) 

And remember, next time you feel inexplicably angry, treat yourself to a snack before blowing up. Your brain and your coworkers might thank you.

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Manish Swarup / AP file

"Ghost chili" peppers, pictured here at Changpool in the northeastern Indian state of Assam, were recently named the spiciest chili in the world by Guinness World Records

By Katharine Gammon
Life's Little Mysteries 

In a contest that matches humans against some of the world's hottest chili peppers, no one wins. Recently, restaurant in Edinburgh, Scotland, held a competition to eat the extra-hot Kismot Killer curry. Some of the competitive eaters were left writhing on the floor in agony, vomiting and fainting.

According to reports, two British Red Cross workers overseeing the event at the Kismot Indian restaurant in Edinburgh but became overwhelmed by the number of casualties and ambulances were called. Half of the 20 people who took part in the challenge dropped out after witnessing the first diners vomiting, collapsing, sweating and panting.

So what exactly are the health impacts of eating really hot chili peppers? Can eating too much of the spicy stuff kill you?

To answer this question, Life's Little Mysteries turned to one of the experts: Paul Bosland, professor of horticulture at New Mexico State University and director of the Chile Pepper Institute, was responsible for finding the world's hottest chili pepper, the Bhut Jolokia.

Bosland says that chili peppers (or as some call them, chile peppers) can indeed cause death — but most  people's bodies would falter long before they reached that point. "Theoretically, one could eat enough really hot chiles to kill you," he says. "A research study in 1980 calculated that three pounds of extreme chilies in powder form — of something like the Bhut Jolokia — eaten all at once could kill a 150-pound person."

This scenario wouldn't likely have a chance to play out. "However, one's body would react sooner and not allow it to happen," Bosland said. "One would have to eat it all in one sitting," he says. Taken over the course of a year, those three pounds of chilies wouldn't be harmful.

Chili peppers cause the eater's insides to rev up, which can come with some problems. They activate sympathetic nervous system — which helps control most of the body's internal organs — to expend more energy, so the body burns more calories when the same food is eaten with chili peppers. "Eating chili is associated with increases in metabolic rate and thermogenesis," says John Prescott, a professor at Sussex University and editor of the journal Food Quality and Preference. "Capsaicin, the active ingredient in chili, does cause tissue inflammation so the mucosa of the stomach or intestines might be damaged by a sufficiently large dose."

Tissue inflammation could explain why the contestants in the Killer Curry contest said they felt like chainsaws were ripping through their insides. Too much of the spicy stuff can also give you a good case of heartburn.

When it comes to spicy, enough of the hot stuff can cause damage — so eat carefully out there!

Related:

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• Why Does Your Nose Run When You Eat Spicy Food?

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Max Rossi / Reuters

New study uncovers why fatty foods make you less sad.

A bowl of ice cream. A giant serving of mac 'n' cheese. A plate of chocolate chip cookies. We already know that fatty, comfort foods can help bust a bad mood -- but new research from Belgian researchers gives new insight into why.

Turns out, there may be more at play here than the visual, psychological effects of seeing the ice cream (or the pasta, or the cookies, or -- insert your go-to comfort food here). The study, led by Dr. Lukas Van Oudenhove of the University of Leuven and just published in the Journal of Clinical Investigation, suggests that it's the fatty acid itself in those foods that works to decrease sad emotions.

Researchers recruited 12 healthy, non-obese volunteers, who were studied the morning after a 12-hour fast. Each individual underwent four 40-minute fMRI scans (that's functional magnetic resonance imaging -- or scans that measure brain activity). Here's where it gets kind of lab-rat-like: The participants were hooked up to a gastric feeding tube that administered 250 milliliters of either fatty acid or a saline solution. But three minutes before they were given the intragastric infusion, researchers played the volunteers 11 pieces of sad classical music, of 1-minute duration each. At the same time, 10 sad faces were projected onto a screen in front of the volunteers.

Without knowing they'd just been gotten a hit of fatty acid, right to the gut, those volunteers reported feeling 50 percent less sad than the ones who got the salt solution. The researchers also found that the infusion of the fat solution to the stomach lessened the behavioral and nerve cell responses to sad emotions. As Van Oudenhove explains, the novelty of this study is that the researchers believe it was the first to determine that fatty acid itself works to brighten a bad mood -- even without the visual cues that come from seeing a cheeseburger or a cupcake.

OK, but it's still a lot more fun to indulge in your favorite foods when you're sad. What's your favorite comfort food? Leave a comment telling us what it is and whether it cheers you up.

Follow msnbc.com health writer on Twitter: @melissadahl.

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